a good instructorI know our snowsports directors try to match an instructor with the student.
Your friend may have a preference. A good rule of thumb is an instructor who has something in common with your buddy; age, background, lifestyle. When you go, look for an instructor who is qualified to teach your friends skill level as well. ( I know many qualified and experienced level one instructors who do not have the desire for another pin, so dont rule them out, but a level 2 or higher instructor will likely have more "training") I personally would take a lesson with a mentor type, older, wiser, etc. but some folks feel more comfortable with someone closer to their age. Gender is not a factor for me.
Dont feel weird about talking with the director (who is handing out lessons when you go)about what you are looking for. Thats important. Then he or she will have a better handle on who to match your friend with.
We always like to see folks who have benefitted from instruction, and like to spread the word. Enjoy the slopes!