Have to agree with previous posters... take lots and lots of practice tests...
As far as physical sciences goes, I have to put in a plug for "Understanding Physics" by Isaac Asimov... It really helps you deeply understand the material, which I think really is the difference between scoring <=11 or >=12 on the physical sciences section.
For bio, do tons and tons of practice questions...also, if you get the chance, take more upper level bio beyond what is the minimum requirement for med school. Not only will it help you in med school, but it helped me significantly (+4 points) when I took the MCAT the second time around.
If you get the chance, (and have the time) try to not only memorize formulas, but understand the effects of changing parameters in the formulas conceptually... test yourself by thinking about all the different ways that you could change something in the formula, and what the effects would be.
-ttac