First of all, SAT is way different than the aptitude test on Matric. It's a bit harder. Second, the harder part is the English part, reading and writing. The reading one you can tackle and become efficient by reading a lot of books actively, meaning concentrating on the words and asking yourself what you're reading. The writing part, quizzes you on the rules of grammar, which you can grasp from any grammar book that focuses on SAT grammar. This one is easier to master than Reading. I would advice you to read SAT Black Book, and Erica Meltzer book on SAT Reading and also SAT Grammar. For SAT maths, you just have to practice. There are books that will help you, but I forgot the title, a quick search on google, will lead you to them. Use @libgen_scihub_bot to get the books. And Good luck.