When are you writing your LSAT? What supplementals do you have now?
A Princeton Review book won't push you to 20 games automatically. Rizz, that is just bad advice. Some people struggle with games more than others...I still sometimes don't get 20 right; in fact, sometimes i still score 17-18...and that is with 2 months of practice.
If you need just a 158, you don't need a course. The LRB, the LGB, and lots of practice tests will get you there. Then you need to work on the questions you get wrong, and work on old games, slowly improving your time while still maintaining accuracy.
the LGB is good simply because it will teach you the notation you need and how to diagram certain statements. And how to pick out the easier games.
LRB should give you methods that will increase your LR score by 2 points (i would imagine) at a minimum. Verbal comprehension is hard to say...depends what is burning you (time or question difficulty).
Let me know,