ACT prep

The typical strategy for the SAT vs. ACT is to take both, see which one you score better on, and study for + take the better one. For me that one was the ACT.

I was lucky, I knew basically all of the math/science knowledge from my classes. If you don't, I recommend taking the time to learn as much of the math/science topics as you can. 

The best think to do then is to practice, because most people (me too!) run out of time even if it's their second…or third time. I recommend the "BIG RED BOOK," the official book by the makers of the ACT. I was happy with my scores the first time, other then for the math section so I literally only did all the math sections of the Big Red Book's practice exams. 

One could always look up practice online, but except for the science questions one can jump even 10 points just by practice. The science section is 70% reading graphs/understanding experiments. 30% pure science (recognizing sex-linked genes, knowing momentum=mv, etc.).

Good luck! Practice and remember that at a certain point, once it's over, you'll never have to take it again!