The key is to pay close attention to the vital signs. They are often the clue to the mystery. I found this great table from EM Clinics of North America by Dr. Timothy Erickson from 2007. I can't imagine how long it took for him to create all these mnemonics. I'll never remember these mnemonics, but they're fun to read nonetheless.
Feel free to download this card and print on a 4'' x 6'' index card.