Firstly I advice him to prepare his interview correctly. There are a differents thecnicals to make it. For example most of interviewer ask people similars questions like:
-which are your best qualities?
-what will you do if you were selected?
-which arees do you think you need more traininng?.
-What do you know about our company?
It seems a silly thing but if you prepare it, you transmit more confidence and it’s very important for you. When you finish interview you feel you have made a good interviewer although the job wasn’t for you.
All people advice not to be nervous but I think it’s always impossible.
Finally I’ll say him good luck !!