Learn the following ahead of time if you want to impress:
Pediatric Head Injury Guidelines (when to scan, when not to scan)
http://www.aan.com/professionals/practice/guidelines/pda/Concussion_sports.pdf
Salter-Harris classification of fractures
You should be able to look this up easily. Here's one: http://emedicine.medscape.com/article/412956-overview
Guidelines for evaluation of febrile infants (specifically when you do a full w/u for sepsis, and when you don't)
This is actually a tough one as this is a constantly moving target. An article written five years ago may be dated. Understand some basic concepts, but understand the challenge, especially in infants aged 30-90 days. Also understand that local practice patterns and individual practice will heavily influence the management in this age group. Cincinatti has some nice EBM guidelines that they follow locally and are good reads (In the past I have especially liked the fever, asthma, gastroenteritis, and bronchiolitis guidelines. Others may be very worth reading.) http://www.cincinnatichildrens.org/...vidence-based-care/evidence-based-guidelines/
In addition:
always check your ears and throats of febrile kids, regardless of CC
check throats of your belly pains (could be strep)
Also understand the ages in which strep usually is present and in which rheumatogenic strains might be present. Also note that viral illnesses (esp. EBV) can cause (and often do) the oropharyngeal PE findings that look like strep pharyngitis (i.e. PE sucks for diagnosing strep). Up to 20% of people can be asymptomatic carriers of strep. Knowing what symptoms/signs tend not to go along with strep pharyngitis is helpful as sore throat is a common CC esp. with those seeking primary care in the peds ED.
always remark if a kid is playful/interactive or not.
always have a disposition in mind when presenting (discharge, admit, observe).
Don't be dependent on the WBC. Not a strong marker of sick v. not sick in the ED setting.