Whether your interest in martial arts is sparked by wanting to get in shape, self defense or just historical, it is vital that you obtain a reputable source for your information. With the multi-million dollar industry in martial arts movies and books available it is easy not only to be taken advantage of by crooks and fakes, but also to get lost in a sea of false arts. I have been in Black Dragon Ninjitsu for almost all of my 27 years of life. The countless "schools" or "dojos" I have seen have rarely supplied any real aspects of self defense or butt-kicking get me in shape help at all. If you are looking for instructional material in book or video form (its just not practical for everyone to join a live class) you need to know what to look for. Make sure your art of choice is not just what is popular at the movies. I cant tell you how many Ninjitsu dojos appeared after the movie Bloodsport hit the big screen. After J-Lo introduced us to Krav Mega in the movie enough, the instruction of the Isrelli martial art skyrocketted. Second, make sure the instructor in the course is a certified instructor in his chosen art. If your goal is strictly to get in shape, see your doctor to make sure that you are physically able to perform what is offered. If you are applying your instruction to self-defense, it is vital that you dont accept a "flash" art. Flying and spinning kicks may look pretty on screen but are not practical on the street. Turn your back on someone on the street and you're dead! One other way to know what you are buying is to research the art itself and the background and history of that art. Obviously for self defense applications, the art of the do-do bird might not be the best choice for survival!!! So choose wisely and carefully before jumping into something that might get you hurt!