+1 on everything above, plus a few things.
Factoring! Factoring! Factoring! Did I mention that it's important to know how to factor accurately?
Know how to work with quadratics, and practice completing the square too--it's useful. Don't forget your point-slope and slope-intercept forms and how to interconvert between them. You'll need to know how to calculate the formula of a line when you know just the slope and a point.
Also, you'll need to be solid with logarithms and exponents--take the time to review the properties of logs and exps now. Know how to work with logs of bases other than e (although e is the most used) and how to interconvert them (change of base formula.)
If you struggle with absolute values and inequalities, you'll struggle when you need to study the epsilon-delta proofs.
+1 on knowing your trigonometry. But I found that if you're even half-competent in trig, it's the algebra that kills. My college algebra professor told her class that "to really learn to DO algebra, study calculus." Words of truth. Algebra+trig is the language of calculus.
Study the inverses of the trig functions: arcsin, arccos, arctan, etc. Know what they look like on a graph, how they relate to their parent functions, and know their domains.
If you plan on going further in Calculus, then you'll need to remember trig identities also, so start re-memorizing them now (especially the pythagorean, double-angle, and power-reduction.)
It's definitely helpful to remember some formulas from geometry: circumference/perimeter of a circle/square; area of a rectangle/triangle/circle; volume of a cube/cone/sphere; etc.
The first chapter of most calculus books is an succinct review of relevant topics in algebra and trigonometry. Use it as a pre-calc. study guide or as needed for review; either way it's a valuable resource.
Good luck! I thought that learning to take functions apart (taking the derivative) was fun; and now I'm finding that putting them back together (integrating) is even more fun! :)