I usually take inspiration from myself, my surroundings(people in my life), and usual traits I like to use for my characters(observant, lazy, reserved, vulgar, etc). After that, I simply imagine myself as that kind of character; I put myself in their mind. I think of what they might do in certain situations, what they would say in response to questions, how they might act when such and such happens. Pretty much, I [i]become[/i] the character I am writing for. Sure, sometimes I come up with carbon copies of certain characters, but that's my formula and it has not failed me this far into my RPing career(10+ years).