What are the best ways to study for the ACT?

There are not as many resources as for the SAT. What review books are the best to prepare?

I took free practice test from Kaplan, Princeton, and The Official ACT. All of these websites offer 1 free practice test, online (or in person) classes, and test books. You can buy any of their books from Amazon.com for a decent price

Take tons of practice tests and review the answer explanations, even for the questions you got right.