If you are lucky enough to have a session zero, make sure to be utilizing that time.
If you jump into a game and don't have time to prepare a character, that's okay. When you have nothing to work with, you can help out the other characters work toward their goals. It's great to be a supporting player, as long as you are consciously making decisions and using your abilities that help out the rest of your party. The DM will definitely make it clear where your party needs to go.
It's totally okay to develop your character in game. It happens all the time. Players are always making decisions about their characters during the game. Let them evolve naturally instead of trying to force every personality detail right away.
The more time you spend with the character and the more encounters they are exposed to, the more you will get to know them.
If you do have a catch-phrase, I would suggest making it reflect you characters goals or alignments.
Captain America says "I could do this all day." This shows that he will always stand up to bullies and never back down.
Maybe your catchphrase reflects what you believe in or what you care about. "Night gathers, and now my watch begins. It shall not end until my death. I pledge my life and honor to the Night's Watch, for this night and all the nights to come."
Or a specific philosophy, "Do, or do not, there is no try."
You don't need to read that deeply into it. "I’m really bad at stealthing. We should go."
–Scanlan, Critical Roll episode 6.
How about a fighter or barbarian who says, "It's clobberin' time!" Ben Grimm knows what he is good at and isn't afraid to say so.
Say something that reflects your goals. "You killed my father, prepare to die."
What specific actions or habits does your character have?
How does your cleric or wizard meditate? What does it look like when they cast their spells?
What does your character do when they are spending alone time standing watch? Does your character have a victory dance they do after they make a kill? Are they obsessed with making sure all the adventuring gear is organized?
Do they take time to talk to horses or other pets? Is your character always using magic to change their hair color?
Does your character keep a journal? Do they write poems or songs? Are they always doing some kind of research?
Does your character like to whittle or carve wood? Make toys? Forge weapons? Tell stories? Buy low and sell high? Knit sweaters? Make jewelry? Constantly make bets? Flirt? Host parties? Wear costumes?
Making small character habits will prepare you when you need to make more drastic choices.
Use actions that don't disrupt the game flow or stop other players from doing what they want to do.
Simple choices can be made to participate in the game. These pre-prepared actions give you something that you are ready to do instead of having to improvise.
What are your characters social circles?
being part of a group or a club gives your character something to talk about and connects your character to the world.
Is your character part of an athletic or a golf club? A group of adventurers? Do they frequent a specific tavern or coffee shop or weapon smith?
Do they hang out with old college buddies on the weekend? Are they a part of a study group? Are they in a choir or a acting troupe? Do they gamble or attend a poker night?
Or maybe your character wants to get back to town just to have a drink with the boys.
Being part of a social circle makes your character more connected, you could get help or contacts you might not normally have. Having your character be initiated into a specific guild or legion could become a huge plot point.
Give your character a specific item that they can't live without.
This is another thing to prepare for before the session starts. Another trick to have prepared instead of improvising.
Arthur Dent just wants to find a good cup of tea. Sam-wise always has his pots and pans with him. Gandalf is always puffing on his pipe.
Maybe your character has a pocket watch that belonged to their grandpa. Or a locket with your lovers picture in it.
Get specific weapons or armor that you can't leave without. Or other accessories. A very comfy robe you need to travel with. Or that impressive cape you like to wear to parties.
If your character is awkward at a party, you can tug at your fancy cape, or fiddle with your necklace.
Hold up your holy symbol and pray to your gods that the awkwardness will end soon.
Bring a real life props to the table.
Having something specific that your character plays with gives you something to focus on when you don't know what else to do. If you don't have a plan, fall back on sharpening your sword or tuning your lute.
Don't think about how intelligent your character is, instead think about how your character is intelligent.
Everybody is smart in some way, or an expert in some specific area. Make your knowledge and skills mean more than what is on your character sheet. With your DM's permission.
This isn't limited to what you get from your class or background. Your characters skills go beyond just a profession. I'm talking about what your character enjoys and excels at.
Do you know how to play five different musical instruments? Do you know all the landmarks between here and the mountains? Can you track every deer trail and footprint you see?
Can you read magic without a second thought? Can you navigate your way through any social situation?
You might not be able to read but you know all the critical areas of the human body and know exactly where to strike. You may be knowledgeable about 17 different types of poison and their effects.
Maybe you can recount every bit of gossip or scandal in the royal court? You can talk endlessly about the history of the region and never be bored of it.
Can you identify 53 different species of monster or magical creatures and list their weaknesses? Do you understand all the trade agreements from 7 different countries?
Do you know how to sail a ship? Identify weather patterns?
Is your character a talented artist or sculptor? Can you brew potions and recognize every spell component?
You might not know how to act in front of the queen, but you can forge the strongest sword out of any type of metal available.
These ideas can be another weapon in your arsenal when you want to contribute to the story or you don't know what else your character can talk about.
What subject is your character an expert in.
Figure out what your characters likes and dislikes about themselves.
Are you proud to be a dragon-born or ashamed to be half demon? Are you hiding the fact that you are half-goblin? Do you agree with the fact that your fellow dwarves might have dug too deep?
Do you support your elfin nation making alliances with the orcs?
What part of your backstory are you ashamed of? What does your character regret?
What abilities do you resent? Are you ashamed of being born as a sorcerer? Do you hate the fact that you can sing to inspire people? Are you constantly healing people that don't deserve being healed? Are you dismayed of turning into a rage monster whenever you get angry?
How does your character react when they know they can't do something? Or fail to do something? Are they afraid of change or scared to try something new?
What about your backstory are you the most proud of? What do you like to brag about?
Knowing what your character likes or supports, goes a long way toward knowing how to react and respond to specific situations during the game.
Set the Scene. Ask players about their characters.
Now that you have more inspiration prepared about your character, you need to put your character into the action. Don't be afraid to start a conversation or set the scene. Relate your character to the other characters.
If you want to role play, you can't do it by yourself, involve others in it too!
Ask the monk where he learned how to fight. Ask your wizard why he wastes so much time reading. Talk about your family or why your character wants to protect innocent people.
Ask another player why they need that fancy cape at all the parties.
Have your character tell the other characters what they care about. Show off your magic sword you got from the holy order of knights. Talk about why the pots and pans always need to be clean.
Tell other characters why you are so good at picking locks. Brag about your favorite things in your backstory.
Tell the players that you are ashamed of being a sorcerer and you didn't choose to be born with it.
The more you work with others to develop characters the more they will work with you too. This is how character moments are created together.
A good DM will let the players role play a scene without interrupting the players or rushing the plot forward.
Support and react to other players actions.
I am always baffled by how many players don't do this. Your party is travelling together, camping out together, fighting side by side constantly, and yet so many players don't react or play off of the other characters.
A great game master, who wants to emphasize roll play, will always be reacting or responding in character.
React to other players stories and support their character arcs.
If you want good role play and character development, this is how you do it. Create friendship and camaraderie with the party members. Grow your personalities and interactions together!
Include the other characters in your story!
Interacting with other players characters will create so many chances for good role-play and too many players don't even think about this!
React to your friends making a great kill or executing a creative plan.
Support other players when they are role playing, get involved with the conversation. If you aren't good at improvising, have catch phrases and other stuff ready to use.
Work with your DM and players to create your characters story. You should be helping them do the same.
If you want to plan a character arc, make sure the group knows about it.
If the party knows what is going on, they can, and should be helping you out with your character development.
Especially if your character is insufferable. Make sure the other players know that your character will learn his lesson. This way the players will actually be patient with you when your character acts like a jerk.
Other players can then make informed decisions and role-play their reactions, based on where they know your character wants to go.
The DM can work with you to prepare specific scenes and opportunities to role play towards that goal.
Work together to emphasize characters abilities.
Ask other PC's to help you out.
Get the fighter to cause a distraction. Ask the rogue to scout ahead or pick some locks. Ask the cleric to turn the undead. Ask the bard to help talk your way out of a situation.
Work together with other players to plan ahead and use each others' skills to support each other. This is why it's a group game.
Take advantage of your skill proficiencies, spells and racial bonuses. These are what makes your character unique. This is how you contribute to working with the party.
Do not dismiss other players' ideas.
Be inclusive, adaptable and supportive.
Let other players try out their ideas. Next time you have a creative idea they might listen to you.
The crazier the idea, the more interesting the game will be. Tabletop RPGs are designed to allow freedom of creativity.
If you are denying creative freedom, you are denying a main element of the game and denying what makes the game fun in the first place.
If players are afraid to be wrong, or make the wrong choice, they won't be able to create anything. Be supportive so you won't be the reason why people are afraid to be creative.
Get the hint! React and respond to the story.
If the NPC gnomes tell you that their friends were kidnapped by goblins, you should get the hint and maybe go save them.
Getting the hint means moving the plot forward. Ask questions. Why were the goblins kidnapping people in the first place? Why are the goblins working with a bunch of skeletons?
What happened in your tragic backstory that is relatable to this situation?
When anyone is talking about their character or their goals, there is a chance for role play. Get the hint and start interacting.
How does it make your character feel when the bad guys plans are revealed?
How offended are you when someone raises the dead? What is motivating you to catch the bad guys?
Are you scared or nervous when you find a terrible cursed item?
Make sure you have clear actions that support your characters goals.
Having a cool backstory and a goal doesn't mean much if you aren't including it in the game. Use your goals to drive your character and the role-playing ever forward.
Use backstories, goals, and alignments to inform your characters decisions.
Use your backstory to relate to other characters and whatever else is going on in game.
Make sure you and your character adapts to the group dynamic and play style.
You need to know why your paladin is willing to travel with a bunch of thieves. Why does your necromancer work with a group of clerics? How does a wizard work with a bunch of hack-n-slash barbarians who can't read?
Adapt to the DM's style of play. If the DM wants a game about killing monsters and you want to role-play, put some effort into making a compromise and work together.
Some of the best role play I've seen is during battle. Don't just attack on your turn during battle. Take advantage of the spotlight on your turn to role play as well as fight.
Make sure the DM knows how you want to play so you both can adapt to each others styles.
If the Dungeon Master doesn't know what you want out of the game, they can't give it to you. It's your job to communicate to them what you want and how you want to play.
If that doesn't work, you need to find a different group to play with.
All of this goes along with
how to be a good player in general.
Be responsible for your character.
Be responsible for moving your story forward. Your character won't evolve or grow unless you put effort into cultivating them. It is your responsibility to continue moving forward.
Be proud of what you create. Be confident in your choices.
The more confidence you have, the more realistic your character becomes.
Don't rely on the DM to remember that you sent a love letter to your main squeeze. Remind the DM that you are waiting for a reply. Ask the DM if you recognize someone specific from your backstory.
The more you ask about things, the more likely the dungeon master will add things in for you.
Take your special magic sword to the blacksmith for repairs. Go home to visit your family. Create your potions and scrolls. Look for leads to solve a mystery. Find out what kind of enemies you are fighting next and get their weaknesses.
Do not wait for the DM to say what you are going to do. You need to take action and make decisions for your character. Ask if you can try something. Tell the DM what you are planning on doing.
If your character isn't making decisions or taking action, you aren't role playing.
Deciding to stay back at the farmhouse while the rest of the players continue the game without you, is not a decision. If you choose to stay behind, you deserve to be left behind.
The DM can only give you so many options as far as where to go and what to do. Make smart choices based off of those options.
You are responsible for how much role-playing you want to do and how much fun you have with it. No one else is going to play your character for you. No one else can control your attitude at the table.
Remember why you are playing in the first place. Have fun with it.
The more effort you put into the game, the more you will enjoy it.
Lets face it, you will have to improvise a little bit.
In fact you will probably be improvising a lot, thus is the nature of the game. But you can be prepared for it. And practice it.
It's okay if you aren't good at improvising. Use these tricks, your backstory, and your characters goals to inform your decisions.
It's totally okay to plan what you want to say beforehand or follow another players' lead. You can even print out the ideas here or other character questionnaires to motivate you in the midst of the game.
As long as you can interact with the game you will be role playing.
When you don't know what to do, have something prepared that your character can say or do. This gives you something to fall back on. Your character can play with props, do a little dance, using specific sayings, etc.
Put some effort into your game. Experiment with what works and what doesn't.
You'll never get good at anything if you don't test things out and practice. It's okay to experiment who your character is.
Trying new things is the only way to grow and learn.
Don't be afraid to change something you don't like about your character. That is what experimenting is.
Practice asking questions in character.
Practice relating your character to the story and ask how they feel about what is going on.
Practice improvising.
Take the time to listen and allow other players to role-play. Don't dismiss others ideas. This is a group game and everyone deserves a chance to role play too.
Drive your characters story forward.
Use these skills to find out who your character is, and what is working for you.