A quick rundown of things to look out for: You'll see a lot of styles with very fluid movements, very similar to Yoga. The problem is that they're generally useless for self-defense. There's a lot of mysticism in martial arts, that results in a lot of very pretty looking, but very useless arts. Also, beware of stagnant arts. Like almost anything, martial arts progress. Just as in gymnastics, the routines you see today are much more complex than 50 years ago, martial arts today is much more effective than it was 50, 100 or 500 years ago. A lot of arts stop evolving at the point when the founding master dies, and what was once a very effective art becomes obsolete. Next, especially in Tae Kwon Do and Judo (but not in all schools of those arts, and also in some other martial arts as well), be weary of overly competition/sports-oriented schools. Competition martial arts is done for points, rather than for the artistic (self-development) or marial (self-defense) aspects. People in sport (Olympic) TKD will fight with their hands down, and avoid certain techniques for less effective ones due to how scoring is done. Likewise, in sport Judo, a lot of competitors will fall in unsafe ways when thrown, since the scoring system requires a clean throw. Now, you'll be find there are two general categories of arts: * Grappling: Judo, some Jujitsu, Wrestling, Shoot Wrestling, etc. * Kicking/Punching: Karate, Tae Kwon Do, Kung Fu, Boxing, etc. As a practical matter, to effectively defend yourself, you'll want to some extent know both. Some people favour one, and others the other, but not knowing any of one will kill you in a fight. I've seen Judo black belts consistently put themselves in positions where they are vulnerable to getting their spines broken with a good punch, and Tae Kwon Do black belts putting themselves at risk for a trivial take-down/choke-out. Furthermore, if you're doing karate against someone who knows both, you will be fighting with the constraint that you cannot allow the distance to close. Likewise, if you're grappling with a kicker/puncher, you will not be able to disengage. This puts you at a very significant disadvantage both ways. Furthermore, real fights place large numbers of constraints on you -- for example, Tae Kwon Do is almost useless in a constrained space. On the other hand, grappling is almost useless against multiple attackers. The best way to do this is to start with one or the other, do it for about 2 years, and then add the other. They have very different ways of moving, so if you try to learn them simultaniously, it'll take longer. You want your body to know one before you learn the other. Also, you'll probably want to avoid arts that teach both. In almost all case, one or the other (or sometimes both) end up being degenerate, and not very well taught. You'll find a lot of bogus claims from both camps, but in my experience, more so from the grappling people. First, especially the Judo camp, emphasizes how safe grappling arts are. As a practical matter, I've seen far more people injured grappling than in a well run punching/kicking art. Properly run punching/kicking schools are, quite counterintuitively, one of the safest sports you can participate in. Next, they'll give a bogus statistic about the number of fights ending up in grappling (no such statistic exists). Finally, they'll tell you that it's about leverage, and that size and weight do not matter. That's the ultimate lie; size and weight make a huge difference in almost every martial art, but much more so in grappling than punching/kicking (where there's a tradeoff primarily between range, for tall people, and speed, for short people, and where range wins out at beginning levels, and speed at advanced levels). In punching/kicking arts, mostly you'll want to look out for overly light/commercial schools. A lot of schools will only focus on the fun parts of martial arts, in order to attract/keep more students. As a practical matter, to punch and kick safely, you need to develop the body strength and flexibility to do it. Especially towards the beginning, the classes should be very intensive. Also, it's critical that the classes have a good warmup. While it's usually possible to throw a good kick/punch safely without one, 95% of the time (otherwise it'd be useless on the street), some small portion of the time you'll end up injuring yourself without the warmup. A pulled muscle can permanently reduce your flexibility (speaking from personal experience). Developing good abdominal muscles is also critical, as are good lower back muscles. While on the topic of commercialism, avoid signing any sort of long-term contracts. 90% of people do not stick with a martial art, and those are designed to rip people off. Even if you plan to stick with it, you might want to reconsider training at a school designed to rip people off. Next, look out for schools claiming to teach the best/ultimate style. There is no such thing. If there was, we'd all practice it. To some extent, different styles are better suited to different people, and several styles are notably worse than others or degenerate. But if you go with one of the normal styles, they're pretty much equivalent in effectiveness. Next, ignore any claimed qualifications. There are about a million organizations for giving out belts, so some systems give a black belt in a year, whereas others take 8 (of equivalent training). Likewise, some have plenty of tenth-degree black belts, whereas others max out at maybe 5 sixth degrees in the world. Likewise, competitions are meaningless, also because of the large number of "world championships" of different sorts, and more so, the large number that are effectively rigged (due to complex martial arts politics, this is often necessary for entirely ethical reasons). The best way to evaluate a school is actually by talking to and looking at the students. See how good they are after 6 months, a year, and three years. See what attitude they have. Ignore what the instructor tells you. If you can, take along a friend who does martial arts, and see what they thing (the danger being that many people who do martial arts are incompetent to judge, since they went through a bad school). One other thing. I lied about strictly two categories -- There is a third sort-of-category: * Self-defense schools. Krav Maga, some schools of Jujitsu, etc. These basically drill some self-defense techniques (eye-gauges, groin kicks, etc.) through massive repetition without real sparring. This is a different theory of self-defense. The basic idea is that the partner punches, and you do a take-down, or throat-gauge or something in return. This is a very different theory to sparring -- sparring is responsive. The opponent does something unexpected, and you need to learn to predict what the opponent will do, and quickly figure out a response. The self-defense schools are static -- you practice against a punch, with the opponent generally not following up, or the opponent doing a preset set of techniques. This is the only way to learn/practice unsafe techniques (eye gauges and knee breaks can't be done in sparring). It is the fastest way to understand basic self-defense quickly, and is useful for any martial artist to have gone through and have in muscle memory at some point in their martial arts career. However, in itself, most of these styles are very limited and can be reasonably mastered in about 6 months. Without the responsive exercise of sparring, you will be very ineffective against a well-trained opponent. Now that we've gone over the complexities of it, I'd stongly encourage you to give martial arts a try. It is one of the most rewarding things I've done in my life, and it is well worth pursuing. Don't worry very much about finding a good style, but find a good school and a good instructor. If you feel something isn't right, feel free to switch schools until you've found one you like. Be aware that martial arts, as most other forms of athletics, is largely about training your body, and there is a lot of hard work. But in the end, it is termendously rewarding, and no matter where you are, with a good school, in a few years, you'll find your body can do things you never imagined possible.