There is debate among fans as to whether or not to hire a coach. For us, the debate is similar to the belief that chess engines can replace a chess master for game analysis. There is a perception that persists, that the best coach is the one who plays the best chess. However, the thinking processes of the newbie and the grand master are on two entirely different planes! The master may be used to dealing with abstract theory and concepts but the new player is still struggling to lay down a solid foundation to build upon. Imagine how ineffective it would be, for both parties involved, if a mathematician at NASA were to teach 4 year olds how to count.
The best person to teach a beginner is someone who is not particularly strong but is in love with, and understands, the game. As the beginner advances, he will want to work with someone 150-200 rating points above him (300 maximum). Any higher than that, and the experience may become strenuous for both as they simply may just not understand and communicate effectively with each other. Of course, there are exceptions.