Study, take practice ACT's, take it multiple times (I took it 5 times overall), and get a good score the right way.
Honestly there's no better way to do it than that. The practice ACT book i got was made by the same company that administers the test and had 5 practice tests inside. I finally got mine after taking the ACT 4 times and getting the same score 3 of those times. After going through the book, I raised my score 2 points to get what I finally wanted to get my scholarships.
Studying will payoff 100000x better than trying to cheat the system every time.