Which books?
Where to get a lot of practice problems from ?
The 12 practice tests in blue book are not enough.
Where can I get a lot of practice problems from ?
I highly recommend the official Online Course. It has another 10 full-length tests, and also has a bunch of one section quizzes + lessons for each topic in math (Algebra, Geometry, Stats, and Number Theory).
The only problem is that it’s all online, so you won’t get a completely authentic experience in terms of bubbling things and writing over the diagrams. This especially matters for geometry, where reproducing an entire figure on scratch paper can take up an unrealistic amount of time. Also, make sure to write out the essays on paper so that you won’t have the advantage of typing speed and the highlight + delete function.
If you just out the math sections you should be fine with doing the other sections online, though.