I just finished a Trig class, and i have some time before I start my Calculus course. I was wondering, what should I have a solid understanding of that will prepare me for this class?
Solid grasp of algebra, trig, and analytical geometry should do. A smattering of logic wouldn't hurt. You could always try to jump ahead in studying. The book I always recommend for Calculus is Morris Kline's Calculus: An Intuitive and Physical Approach. It's heavily applications-oriented, with very clear explanations, and the price is right.
All important. You might try, as a review, another Morris Kline book: Mathematics for the Nonmathematician, although his initial discussion of Augustine has now been laid to rest.
Perhaps the most important point- you learn mathematics by doing mathematics, not by reading mathematics. When your text gives examples, close the book and try to do the example yourself- and don't come on this forum (or any other) asking people to do your homework for you!