For all exams I recommend primarily using official test materials. You can buy official materials on Amazon for most tests for less than $100 new and less than $50 used. Make sure you are using a current version for your exam. The SAT changed in 2016, and any SAT prep materials published prior to 2016 will be nearly irrelevant. The GRE changed in 2011, but some of the older materials can still be useful.
- ETS makes the GRE. Purchase the ETS Official Guide, ETS Quantitative Reasoning, ETS Verbal Reasoning, the free ETS practice test, and the ETS 2nd practice test.
- GMAC makes the GMAT. Every year a new Official Guide to the GMAT is published with a few dozen new practice questions. Each Guide has about 900 questions. You can buy last year’s Guide used for about $10, and you can download both official practice tests for free on the GMAT website.
- ACT makes the ACT. The Official Guide to the ACT includes five practice tests. You’ll want to do more practice than just this book, though. There are a ton of real but retired ACT tests floating around on the internet. These are the best practice resources.
- Collegeboard makes the SAT. The Official Guide to the SAT, the Official SAT App, the Official SAT and PSAT practice exams, and the SAT on Khan Academy will be the best practice materials.
- LSAC makes the LSAT and the Official LSAC Handbooks.
There are only a few non-official print resources I have to recommend at this time; there are a lot of resources out there. Anything and everything by Erica Meltzer I recommend for all Reading and English sections, whether they’re on the SAT, ACT, or GRE.
For reviewing math fundamentals, I recommend Cliffnotes for Standardized Tests. It can be really difficult to review math fundamentals on your own, especially if you haven’t had math in a while, and if when you last did, you didn’t feel that great about it. Cliffnotes is a good place to start.
For lots and lots and lots of extra practice—not to mention the challenge problems—on the ACT, GRE, GMAT, and LSAT, try Manhattan Prep’s 5-lb books.
For grammar fun and humor, read Lynn Truss’ Eats, Shoots and Leaves. Some of the topics, such as the Oxford comma, that are covered in this humorous read will not be tested on any standardized test, misused apostrophe’s—I mean, apostrophes—will be tested on some exams. Whether you love or hate studying English, you’ll find this book equally humorous as consoling.
Like her books, Erica Meltzer’s blog illuminates the verbal sections of standardized tests.
Forums are great places to learn, commiserate, and celebrate your tests. I love GMAT club, GRE club, and I’ve just started reading Poets and Quants. Have you looked up your test on Reddit?
At this time, I do not have any online courses to recommend. One of my students found Magoosh helpful, but others have not. There are courses on Lynda.com, which you might be able to get for free through your school or employer. There’s also always youtube.
At this time, I do not have any in-person courses to recommend, other than the ones I teach at UCSD.
Did I miss anything? Do you have a favorite course, blog, book, forum, or anything else you’d like to recommend?