I haven't taken the test yet...but coming from someone whose studying with a double digit number of GMAT books and 1000CR, SC and RC the best advice I can give you is this:
1. Participate in the forums. Who cares if you see some of the questions from the GMATPrep test? You're studying to do well on the real deal, inflating or deflating a score on a practice test doesn't matter at all. It's the big test you're preparing for. Besides, you should take one of the GMATPrep tests
before you do too much more studying anyway.
2. Do the GMAT Club Challenges
. Best. Quant. Practice. Ever....PERIOD.
3. MGMAT Practice tests and books are the best out there IMO.
good luck this time around