It depends on the game really - if the game encourages roleplaying I will do my best to participate. If a game has enjoyable and balanced challenges I will be happy to focus and mechanics and try to find optimal solutions.
I generally don't do extremes though - I won't write biography for my characters. Just figure out broad strokes - personality, alliegances, believes, biases etc.
Similarly, I am not a minmaxer or powergamer, but I do try for my builds to make sense, and for party to have synergies.
