hello how old is your son? what martials arts do u have in your area?the most important thing would have to be the instructor i would watch to see how the sensei teaches, does he/she make sure the students are doing the actions right, is he/she aggresive, is he/she qualified to teach, do they spar, how do the students act towards eachother and the sensei. The art might be good but if u have a crappy instructor i wouldnt bother going. how much does it cost for him to go. What is the reason your son wants to learn martial arts?