make sure the school is approved in all states! go by the CA list...
things are getting tougher, and the states are looking for ways to verify that offshore schools are legit, valid, accredited, have oversight, whatever...the toughest credentials to meet at this point are the CA approval. so, by going to one of these schools, you are somewhat protected...
other things to consider:
1. US clinicals
2. residency placements
3. usmle results
then there are many other things on a more personal level, such as where is the school, how big/small classes are, style of education, where the rotations are, etc...but, before you go looking for that custom fit med school, at least make sure that you can come home, and work in ALL of the states when you are finished.
you don't want to get home and have a shrinking list of options, as states start getting more strict. nor do you want to limit your future options before you even have any! big stuff first, than get choosy..
best of luck