Gearing up For Specialization in the USA

In general it is pretty hard to specialize in the USA if you are an international candidate, but it varies a lot with the field you wanna specialize in

I'd say:

OMFS, Ortho, Pedo are the hardest to get in (Good programs more so than the bad ones for obvious reasons)

In general:

#1 Grades, grades and grades (GRE for Ortho, NBME for OMFS)!!
#2 Externships (Mostly for OMFS)
#3 Letters of recommendations
#4 Research
#5 Extra curriculars/Social service/Societies etc etc....

I know its a pretty general overview, but feel free to post if you have any pacific questions!