Please help on SAT Vocab!!!

So for CR, I’m using The Critical Reader by Erica Meltzer and The Insider’s Essential Guide to Critical Reading & Vocabulary. The former has helped me so much on passages, but after taking many practice tests in preparation for the upcoming October exam, I noticed that what’s really keeping my score down is the sentence completion section.

The Insider’s Guide has 600 essential words in the actual book, but I think the total amount of SAT words it contains is 900 because the author included other words within the definitions of the original 600 words. I’ve memorized every single word in this book, but I’m still missing 6-7 sentence completion questions per test. The issue is not really with the logic of the questions, I just simply don’t know the meaning of the words in them.

This book was heavily recommended to me on this site, and its reviews around the web are pretty awesome. However, there’s still so many words that appear on the SAT that I simply don’t know. Does anyone have any advice?