I always used to worry about hugging people. It's the whole under arm or over arm thing that worried me, lol. Some people have a tendancy to hug under your arms, some people do it over arm and some do like a mix of both (usually a lads sort of hug).
sorry silverliner, cant figure out how to quote you properly...
with this, its pretty simply. if a guy hugs a girl, he goes over, and she goes under. it works that way because on almost all occasions, the guys will be the taller of the two. guys hugging other guys is a mix because you should be around the same height, usually. i think universally (i havent thought about it up until now, but thinking about it i always do this) its right arm over, which works out if everyone does it.
dunno if this is any use at all.