Never take a real SAT Subject Test before first taking a practice SAT Subject Test at home. This advice is important because you don't want to bomb an SAT Subject Test since it is hard to take it multiple times with the expectation of doing much better from one test to the next. You either know the content or you don't. Just because you do well in, say, your high school Spanish V class does not mean you will do well on the SAT Subject Test in Spanish because the latter could be testing grammar and other content that don't figure into your success in the classroom. The best SAT Subject Test preparation books are The Official Study Guide for ALL SAT Subject Tests, 2nd Edition if you are practicing a sampling of SAT Subject Test options, The Official SAT Subject Tests in Mathematics Levels 1 & 2 Study Guide if you are practicing for either the Math Level 1 or Math Level 2 SAT Subject Tests, and The Official SAT Subject Tests in . & World History Study Guide if you are practicing for the . History or World History SAT Subject Tests.
Do your SAT prep while you’re feeling your best and squeeze in your regular school homework after that. If you only have time for one and have to choose between SAT prep and regular school homework, do your SAT prep. Of course, you have to do well on your major papers and tests that contribute a lot to your grades, because you don’t want bad grades, but skip the busy work that teachers like to give and realize that there is always some school work that doesn’t have to be done, and much that doesn’t have to be done to perfection.