What do you want this mentor to do. If it is to critique and tell you what to do, then I suggest that this might not be the best way forward. There are no quick fixes in painting and even the best mentor won't make you advance any quicker than you would probably do on your own (having tutors and mentors just make people think that they will get better if they just follow their advice - a bit questionable in my view). Looking at the portrait you have posted here, I would say you are doing pretty well on your own. There is a good intensity in the eyes and the features are all in proportion. You are obviously skilled enough to compose your portrait as a close up view to emphasis the expression on the man's face. Not a bad start, eh? Follow your heart, not a mentor.