I urge you to practice all three OG books. And make sure to use an
Error Log as well. For verbal, especially for SC, it's important to fully read the explanation for each and every question. That means read why one answer was correct and the reason why the others were incorrect. Do this for all of them, even the ones you answer correctly.
It takes time to get used to DS. My mistake was usually assuming too much from the given information. The
GMATClub Tests, however, break that habit. Other than that, just review the math concepts involved. Be sure to check out this link:
best-gmat-strategy-thread-no-discussion-82453.htmlI used all 5
MGMAT books and recommend them. Pick up the Number Properties book. If you like it and have enough time, buy more. But if you're particularly strong in one area (Geometry, for instance), then there's probably no need to buy a book on that topic.