N/L Hold Em - How do I open up my game ?

[screamin_e]

I'm a fairly new player - but I'm poker obsessed. I play quite a lot, host a weekly home game, and read as many books as I can ( Theory of Poker, Super System etc )
I feel like I've reached a pretty good understanding of good starting hands, pot odds, and position at this point.
My problem is I feel stuck in a break even or very small profit style of play.
I hate to say it - but I think I've learned just enough to become a knit !
Any suggestions on how to open up my game more ? How and when to play more marginal starting hands ?