One of the things I learned from making a character for “Burning Wheel” (I don’t know if anyone ever plays that game…no really I don’t think anyone ever plays it they just drool over the books)…“Beliefs and Instincts”. They really are good ideas to help people know how to play their character and also informs the other players of how that character will react. Beliefs consist of one to three beliefs the PC has. A Belief is a characterization, a goal, and how you want to be rewarded.
I will topple my brother the Duke no matter the cost. Topple, Brother/Duke, no matter the cost.
Is something or someone important to your character write it down. Is there something you want to learn about or do you have a philosophy? They make good beliefs.
Make the goals fairly short term, colorful, work together as a team to succeed, don’t despair if you can’t get to everyone’s goal. Use the rest as hooks for other adventures. Succeeding at a goal is probably good for a milestone award.
Instincts are really great for new players stay in character. Make one to three instincts. These consist of a declaration of action in a certain situation. It is an if then statement. “Always, never, and when” statements make good instincts.
I always carry ingredients for noodle soup.
If confronted I take an aggressive stance.
I cast my spells carefully and patiently.
I listen at every junction when underground before proceeding.
When I think I am in danger I draw my knife.
These are good tools for creating a greater depth for your character and are automatic. You don’t have to think about them in the moment. They are already planned out and allow you as a player to immediately respond in character to a situation.