This could be my shortest blog yet.
Practice, then practice some more!
Experience with the test, in my opinion, will help you more than anything else. If you take a number of timed practice tests on your own and see which problems you are missing I can show you how to approach and solve those problems. When you see similar problems you will know how to do them. Remember, the ACT is a concept based test not an intelligence based test. Also, you may find it interesting to know that the entire test can be done without a calculator ...but of course you are free to use one as well. My highest recommendation is to start taking practice tests on your own, see which ones you are missing, review those concepts and repeat. I could tell you all kinds of neat tricks like picking the letter b when you don't know the answer but at best these strategies will likely only add a couple of points to your score. If you are reading this you want to see a jump of 5 or more points, right? Many students resist doing additional work over and above their normal homework load so figure out what type of weekly time commitment you can make and commit yourself to it.
Helping students succeed in math for over 10 years. Individualized attention makes the difference!