For science, read this book https://www.amazon.com/Love-ACT-Science-innovative-standardized/dp/0996832203. I scored 20-23 constantly on the science portion before I read this book. Now, after taking the October test, I scored a 31 in science. This book really opens your eyes to how easy the science test is. It's a short book, so you should have enough time to finish it. A chapter a day ;).
For math, I can't really help you since I have a 25 in it, but I would just say take advantage of the easy questions (first 30). Trust me, you would probably finish the first 30 in like 10-20 minutes and have a lot more time to finish the more difficult questions(last 30).
Reading sucks.
I'm also a senior, and I know we only have 1 more shot to take the test, but you just have to work hard and do a lot of practice tests. You're making an investment in your future by studying. Regret is probably the worst feeling you could have.
I have a link to the Amazon page where you can buy it: https://www.amazon.com/Love-ACT-Science-innovative-standardized/dp/0996832203.
Get these books...they helped me. I went from a 30 diagnostic composite to a 36. Science book is legit. I got a 27 on my diagnostic science section and got a 36 on the actual test. English and Reading books are solid. Math is ok. Good luck.
https://smile.amazon.com/gp/product/0996832203/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
https://smile.amazon.com/gp/product/0997517824/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
https://smile.amazon.com/gp/product/1733589546/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
https://smile.amazon.com/gp/product/0996832262/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
I would recommend For the Love of ACT Science for the science section, as it gives very good strategy. If you do need anything for math, I would honestly recommend the Best ACT Math Book Ever (you can buy algebra or geometry, whichever one you need). It's the most comprehensive one I've found.
Just practice lots of questions. My tutor said to look at the science section like another reading section. DO NOT DO THIS! Look at it as graphical analysis with a bit of supporting text. My practice book of choice for the ACT Science section is For the Love of ACT Science by Michael Cerro. Here's the link: https://www.amazon.com/Love-ACT-Science-innovative-standardized/dp/0996832203/ref=sr_1_1?dchild=1&keywords=act+science&qid=1607053321&sr=8-1
For the love of act science on amazon
The official prep book “big red book” on amazon
I would avoid Kaplan and Princeton review act prep books. If you really want to check them out, they’re at most libraries.
Supertutortv has good book for particular subjects. on their website
For the love of ACT Science
https://www.amazon.com/Love-ACT-Science-innovative-standardized/dp/0996832203
Find it on Amazon--despite rampant PDF sharing on this forum, I don't encourage the stealing of copyrighted books. https://www.amazon.com/Love-ACT-Science-innovative-standardized/dp/0996832203
https://www.amazon.com/gp/product/0996832203 - science (Really helpful)
https://www.amazon.com/gp/product/0997517824 - Reading (Really helpful)
I'm very skeptical when it comes to buying books that promise that they'll help me out. When everyone told me to buy these books, I believed they were lying about how good they were; however, when I read these books, it made the ACT test seem so much more simple. Also, as sk0620 said, taking a bunch of practice tests help out a lot. Every day, I do a section practice test to better my skills.