So you're asking how to do well on the EM rotation and then you ask if there is more to it than scoring well on the EM eval. The answer is no, there isn't more to it. But if you want advice to score well on the EM eval here you go:
Show up early and leave late.
See as many patients as you can.
Try to reduce the residents/attending's workload where possible.
Know the basic differentials for chest pain, abdominal pain, vaginal bleeding, back pain, headache, vertigo, syncope, fever etc.
Read about your patients.
Know everyone's name.
Try to functional at the level of an intern.