read up and get good on EKG's, CXR's, diagnostics of PE's (when to D-dimer v. when to skip ahead and do imaging) , differential of 1st trimester bleeding, when to CT scan a closed head injury, read up on the symptoms of concussions and post-concussive syndrome, Nexus criteria for clearing a c-collar, and work on having a disposition idea for your patients at the end of all your presentations. There's a huge huge huge subject area for EM, but those are all things that will come up on a rotation sooner or later, may be a bit weak for 3rd year med students, and require just a little bit of reading to catch up on.