I've heard that for the Physics GRE, the more problems and solutions you see, the easier it is to recognize right and wrong answers. This might be where the purple book (currently collecting dust on my shelf) becomes helpful, assuming the errors are minimal of course. I don't know if it's worth the price though.
You can also review the examples in your textbooks, and if you still have them, go over solutions for old tests, quizzes, and homework sets.
I don't know if this helps, but these are the best ideas I can come up with. Once I finish the practice tests, I'd like to hear suggestions for what to do next myself.