My big exam tip is to just try it. The exams are designed to test what you know as part of your job, not what you can learn in books. If you go in there to find out where your weak areas are, you might surprise yourself and pass without study! In fact, the best (IMO) SQL exam there is is 70-431 (I should know, I wrote many of the simulation questions). These questions are hard to study for, brain dumps are far less useful for them, and they really seem to test whether or not you use the product.
Since I blogged about my experience in writing the simulation questions, I have been pestered by cheats. They use brain dumps and still fail. My kind of exam.
People who use the product say that it's too easy. Again... my kind of exam.
There's a big discussion going on at Howard Dierking's blog about the source of community questions. I've blogged about it too, so you should be able to find the discussion and jump in.
LobsterPot Solutions & Adelaide SQL Server User Group