Get references from his former students. Was he available, consistent, knowledgeable, can he teach? Did his students consistently pass the ppl check ride? Do they reccommend him? If he is not forthcoming with names and numbers of current/former students, well then that answers the question. As a zero knowledge student you simply have no reference point as to wheather or not you are receiving quality instruction, and the last place you want to learn that is during your check ride. Many of the "local" guys provide outstanding instruction, and with 39 years experience can offer insights that the newly minted time building CFI can't. Ask him his background, is he passionate about teaching or is he just passing time or CFIing rather than working at Walmart in his golden years? You MUST ask these questions. You are embarking on a very expensive and life changing pursuit and your first experience will mold your opinion of flying as a career or a hobby. Get it right the first time and you will continue to love aviation, get it wrong and it will be too expensive and frustrating to continue.