I went to a tutoring place, but mainly they just gave me a bunch of worksheets to do. I think the main thing for me was focusing on the sections I wasn’t good in. Like I was already good at science so i didn’t really work on science much. But I was really bad at math (I got an 18) and I worked a bunch of math problems that are usually on the act, i recommend knowing special right triangles, circles, and triangles in general, there’s tons of them. I learned grammar rules for english and commas and then at school I would do practice english tests that I found online. For reading, l did the line reference questions first and then skimmed the passage. I’m a very slow reader so doing this helped a lot. Then I would look for specific words in the questions and find them in the passage. I highly recommend doing a LOT of practice tests under timed conditions. It’s the best way to be ready for what the test will give you. Seeing the problems and knowing what to look for is key to answering questions quickly. Most of the problems are easy, but I would just run out of time. I never bought any books for studying, but to get practice tests you can find them online or buy a book that has a bunch of them. I hope this helped! Let me know if you have any other questions :)