Bad heads up . . . need advice

This is my first time here. I play a lot of sit n go's online, and find that I almost always place, but rarely first. Usually I come in second. I am playing NLHE for $10. I know that I am weak heads up, so I am wondering if anyone knows of any books out there that could help me. I think my main problem seems to be playing hands like a K2 to a raise. I think I should be playing it (especially when they raise every hand) but I'm not sure. I do fine playing big hands and small cards like suited connectors, but anything else I don't know what I am doing. Any advice would be appreciated.