I think I read somewhere that if you play the best move on the board, the whole offense/defense debate pretty much takes care of itself.
EDIT: Some more brain cells just kicked in. One of the things IM Danny Rensch has said is that as black you need to equalize the position before going on the offensive.
I'm getting mix feelings about playing black. Some of my friends say play defense and some say play as if you're were white. Any suggestions on the true way to play as black?