Yes they are tricky on the real thing too. Often you will end up with a clear low angle and a clear high angle but the two in the middle are only slightly apart. The answer choices don't help either because both options are normally there too.
Best way to practice is exposing yourself. If you have a study partner buy two protractors and make your own angles and then exchange them. Also the software can be bought. I used topscore and Kaplan last time and got a 24, but basically it was all topscore as kaplan was a joke. This time around I have achiever and will probably buy Crack DAT PAT too, though only like the 5 test one I think.