Ive said it before Ill say it again - learn the rules of live poker in the casino you are going to. Online is easy because the computers do all the work for you in regards to the rules - bet sizing, folding, raises and what not.
The biggest one to remember is that verbal announcements are binding - so dont screw around and say AI and think you do not need to make that bet. Also be careful of string bets, acting out of turn, and not raising enough when you want to raise.
Also, since it is live he needs to be weary of physical tells
that people may pick up on - there are many - there are books and online information about these if he is interested. Scared money is super easy to spot and take advantage of, so tell him to not play scared.
Hope this helps