Stefani,
Since you're not a complete newbie at this, I would definitely recommend Perry Marshall's stuff. Any interviews, audio recordings, free courses, etc that you can get your hands on - and of course, the Definitive Guide is *excellent* if you're ready to put down some cash for some good solid info.
I've learned a lot from Perry over the last 6 months. I think one of the best tips was how to save money on Search Network & Content Network ads (by creating three separate, but identical, Campaigns - changing only the bid price). Very good method of tracking conversions from all three sources, too