So, my D has taken the SAT (and an SAT prep class).
Will take the ACT in June.
Aside from doing practice ACT tests from prep books, is there anything else that can be helpful in preparing?
Doesn’t really have much time since she won’t be able to study until after the AP exams.
Thanks!
My son took both the SAT and ACT and said he thought the ACT seemed easier, but he had to work a lot faster. He didn’t finish the math portion on his first try and barely finished the english (still earned a 33). So, for the second round, he really read through the format of the test questions in the front of the book, which I think many kids don’t do. They tend to just take the practice tests. By going through the explanations, samples, and a few practice tests to get his timing better, he went back 4 months later and scored a 36. Also, if she is going to take any of the SAT subject tests, definitely read the front of the study book to see how they are scored, because it is done differently. Goodluck! 
Make sure you time her prep tests. The ACT is much more tightly timed than the SAT, so if you give her an unlimited amount of time for a practice test she may get a rude shock when the proctor calls 5 minutes left on the actual test.