I would not rely on Stine's Handbook of Model Rocketry to study for a Level 2 test. It has some great info in it, but I don't think it's the right recommendation for the test.
NFPA 1127 (viewable for free on the NFPA website) is a good reference, as is the Safety Code of whichever organization you plan to certify through. NAR & TRA tests are different, so what will help you depends on whose test you plan on taking.
With Tripoli, you receive a Study Guide with your membership binder which contains everything you need to know to pass the test. I'm confident NAR has similar information available; I just don't know where to point you to find it (I took the TRA test).
Marc Canepa's book is something I've not seen myself, but I've heard nothing but good things about, so I do think that's a great "getting started with HPR" book that will be a worthwhile investment.
What's your background and experience level, and what organization do you plan to certify through? We can better direct you with that information.
-Kevin