Like what mary said, do LOTS of practice problems. About 99.9% of the people I asked on how to prepare for the PE said to do as many practice problems as you can. My concept was the more practice problems you solved, the higher the probability you will pass the exam. Likely chance that a problem you practice is going to be similar to an actual exam problem. I bought the sample exam from NCEES and solved most of the problems. What really helped me out was the Testmasters notes I was able to obtain from a friend. The notes were helpful, but the practice problems Testmasters give you are GOLD. I believe this forum offers the Testmasters notes for download somewhere. I also solved as many problems as I could from the CERM sample exam. Lastly, I solved as many problems as I could from the CERM practice problems, although some of the problems were ridiculously difficult. Oh, I would like to add to not pay too much attention to the first few chapters of the CERM where they try to review your calculus, matrix, vectors, etc... I wasted my time doing that... Just go straight to the engineering portion.
They tell you to get good sleep the night before the exam, but I was so nervous I couldn't sleep. I think I got like 1 hour of sleep (at most) the night before. If you can sleep well the night before, more power to you. When I took the exam I solved all the problems I knew how to do first, then I hit the books like crazy to find out how to do the more difficult problems, finally my last resort would be to answer "C" on the rest of the problems when time was becoming a problem. TIME is money during the exam, so try to limit your restroom trips to a minimum... Ok, that's my 2 cents on this for what it's worth.
PRACTICE, PRACTICE, PRACTICE and GOOD LUCK!!