For the both sections (and honestly for any section) practice tests are your best friends. The math on the ACT is hard in comparason to the SAT due to the 1 minute/ problem deal and therefore you can't spend more than a few seconds decyphering what skill the problem is testing. The practice tests are built to be a good indicator of what you may want to review before testing; otherwise, you may not know if you get nearly every single trigonometry problem unless you take the time to test under test conditions. It will not be a complete picture (ACT does have a habbit of testing more obscure formulas such as law of cosines), but it should give you an idea of your weaknesses.
The science section is the hardest to prepare for as, outside of skill based componets such as making sure your critical reading is strong, there is very little to prepare yourself for what is actually contained in the passages. The science section is only a much harder reading section; outside some more scientific thinking, most of the skills that got you such high scores on the reading section should allow you to get a high score on science. The other key is to not let yourself get worn out by the section. The ACT is much more of an endurance test than the SAT and therefore the test writters put the hardest section last. As long as you are attentive and focused as you enter the final section, you should have no problems getting a great score. It's hard, but if I can get a 36 on the science section without cramming for it you should be able to get a great score on it too.