I won't try to play any specific karma level. I'll do whatever is more profitable, and what helps me survive.
This is a good policy, especially for this game. I'd like everyone to recall that Karma is de-emphasized in this game, and is simply a way to chart your actions by a moral compass, if you put stock in that sort of thing.
Rather than asking upon what side of the karmic scales will your soul reside, I think it would be a better question to ask what kind of a person will you be in the game.
Will you build an army of loyal followers and allies from whatever factions you support? Will you be a transient drifter who never stays in one place long enough to get caught up in politics? Will you be a neutral loner who just wants to ply his trade, whatever that may be, whether a merc for hire or vender of crafted goods?
Or will you be a hostile loner, more at home in the abandoned swaths of desert, preying upon all you see, only walking into a town with an open hand when you run out of milk?
These are the sort of questions you need to ask.