Young Writers Society

My answer would be: make you a different person.

At the risk of sounding like a broken record, acting like your character for a week would probably land you in trouble - if not with the law, at least with parents and friends. Like many others here, if I were to act like my character, I'd be killing people.

And acting like your character won't make you a better writer. Only time and practice will. You might get a better grasp of your character's mannerisms and so on and so forth by acting like them, but it won't help you describe them more elegantly. Writing and acting are rather different crafts, though some could argue that they are related.

Sometimes I will (in the privacy of my room) do things that characters will and think about how they would react to certain situations, but again, it helps with development, and not actual writing.

I can't say as I've ever held a conversation with one of my characters, though I have played a character in my mind and been talking to another character. Does that count? It's not like I'm the author speaking to my creation, but creation to creation. Always in context of the story too... I don't do that weird break the fourth wall thing where the characters know I created them. That could turn out nasty.
~GryphonFledgling

My characters have established a permanent and somewhat irritating residence in my head, but they don't change my personality. They ramble and talk and bother me when I'm supposed to be concentrating, but I know them so much better that way. Things about them just come to me because they live in my head (yes I know, I'm extremely insane, but oh well. I don't care), and it makes them evolve so much more from cardboard. It's fun sometimes if you have a friend who has characters in their head too to have the characters interact by having both of you act as one of your(and their) characters. My characters have gotten into some interesting messes that way. 'Tis much fun.

Well, I hope that made some sense.

Much love, Ryllie