There are dozens of test prep publications available, but I recommend students use ONLY the official SAT and ACT from the test makers. Both tests have Sample/Practice questions on their websites, ACT and SAT Practice Tests you can download, and Official Guides.
SAT also has a prep program with Khan Academy.
ACT has an online program and has a tie-in with Kaplan.
*I do not recommend using other programs because they are knock-offs and not the real thing. The ACT and SAT practice tests on the websites and the practice test are free and the guides are inexpensive (I’d look for them on Amazon because they are probably available at a lower cost and will get shipped faster).*
DO NOT use any PSAT, SAT, or ACT material prior to 2015 because all these tests have been changed since then.
Stick to the real thing.