The hardest part of the exam is to answer many questions very fast. No matter how experienced you are as a project manager, there is a big chance to fail unless you specifically practice answering different types of questions. If you see a long question with extraneous information, start with reading the question itself (the sentence with the question mark), then read possible answers and only after that start reading the scenario.
There are formula-based questions. Here it's simple - just learn the formulas by heart. There are 40 formulas at most. But most common PMP questions will require the knowledge of about 10-15 formulas. Make sure you know them inside out.
Some questions have answers that all look correct. In other words, there are no incorrect answers. What you need to do is to choose the BEST, most logical answer for the presented scenario. You must differentiate these types of questions and use different techniques to answer them more efficiently.
Practice online with as many PMP sample questions as possible.
Good luck!