I used the jblearning aemt prep site for mine, I wasn't sure that it helped a ton, but I passed my first attempt.
Physiology is a big thing to make sure you are good at, vitals and what ailments correspond to vitals. Alpha, Beta properties, meds, etc. etc.
The biggest thing I didn't like about the test is that they don't have clear cut answers on a lot of questions, it is what is the best of the answers.