What sort of company is he going for the interview at? If it is young and modern, he'll get away with it as long as he wears a suit. If it is a conservative company he'll be better off shaving.
Other hints?? Research, research, research. As an ex-recruitment manager it never failed to amaze me how many candidates turned up for an interview failing to know even the basics about the company that they were hoping to work for.
Look on the net to find out facts and figures on the company. If it's retail of any type, visit a store or buy something on line - do anything you can do in order to show that you've taken the time to research the company.
Most interviews ask standard questions, although they may phrase them differently. There are many internet sites that will show you eg questions - just google.
Certainly get him to think about strengths and weaknesses, why he wants to work for the company, examples of when he's played an effective part in a team (can be at university) - make sure he thinks of lots of examples of when he's done/shown the above. Rather than saying 'I'm calm in a crisis' tell him to have eg's of when this was the case to back up what he was saying.
Make sure he arrives 5 mins early - if he arrives at the venue earlier don't go into reception until 5 mins before meeting. If he's going to be late (cardinal sin) make sure he phones them and tells them.