Martial Arts can be an excellent way to get in shape and learn some of the basics of defending yourself. However, with the wrong kind of instruction it can ingrain some bad habits. You need to be very careful when selecting a Martial Art. It can be prohibitively expensive, and while some martial arts offer a balanced and effective fighting program (such as Brazilian Jui-jitsu), others, such as many forms of internal Kung Fu are questionable. Many systems of Kung Fu have been watered down, and now solely concentrate on exercise and meditation programs, not on fighting/self-defense. Generally speaking, Jujitsu, Wing Chun, Muay Thai, Eskrima, Jeet Kune Do, Silat and other reality based martial arts would be the most effective.There are more options in the form of Egyptian Hikuta and Russian Systema. The following styles, generally speaking, focus on controlled sparring and specialize less on self-defense applications; styles such as Tae Kwon Do, Judo, Karate. There a few things to look for when selecting a martial arts program (Boxing) on merit of self-defense; If you see the class sparring, this is a good sign, particularly if the sparring is "full contact" - meaning, the exchange of blows are, while controlled, fairly heavy. No dynamic stretching before a workout indicates either an inexperienced instructor, as stretching can prevent injuries, or a lighter-contact class, which can also be a sign of warning. Also, look at the instructors; If they seem out of shape, or nonathletic, it could be a bad sign. You should also ask about the instructor's background in their training, lineage, style affiliation, etc. Although it can be a marketing scheme, look for instructors with "hands on" experience with the subject, such as military/police experience, etc. Also it is good idea to train in different disciplines such as Jujitsu and full contact Karate which will teach you both strikes as well as grappling techniques and counters. In real life encounters always grapple to strike and not the other way round.
Avoid Martial arts schools that employ complex flashy movements, such as high level kicks, or charge hefty fees for belts. Although fees for belt testing is common, many are moving away from this system or eliminating the associated fees. Belts are actually a western construct, since traditionally there was only a master or student rank. Street punks are not particularly concerned with belt rank, all they have on their mind is to rob, rape, or inflict harm to you. On the street you are either the prey or the predator.
Warning: Be aware that training in a martial art carries a number of potential disadvantages. The first disadvantage is that many martial artists have a false sense of security. Most martial arts students (as well as their instructors) have never been in a real fight, and they train with fellow students, who do not attack them viciously. Many martial arts instructors, in order to maintain their liability insurance, do not allow hard sparring or hard contact. Therefore, many martial arts students have never been hit like they would in a real fight. Be aware that being hit hard for the first time is a shock to the system. I have seen high-ranking martial artists get beat down easily in real fights, because they went into shock after the first hit.
However, the opposite is also true. I have seen well trained martial artists to take out a big fat guy with a single kick and the fellow landed up in hospital for a few weeks. So take hope, all is not lost. Take your martial arts training very seriously with special emphasis on self defense. One common mistake martial artists make is to get into a fighting stance which telegraphs their intentions. Another mistake is to wait for the other guy to strike first and then try to defend. Be aggressive and proactive with protecting yourself. It is better that ten men are wounded rather than you being killed. Be observant for movements of opponents and notice their shoulder-arm joint. With the slightest flicker you will know an attack is coming and then block and counter the attack as best as you can. Practice this several times in the dojo with a sparring partner.At first do this at slow speed and with a variety of punches at upper middle and lower level.Then do this at full speed sparring. Most schools also teach how to defend against kicks but in this case defending is easier as moving sideways and then blocking and countering is done with a little more time on your side. -A martial arts student
Don't allow your training to give you a false sense of security. Realize that most martial arts schools do not train students to fight for real. Also, do not attempt to fight multiple opponents. Despite what you see in movies, such as when Bruce Lee successfully fights up to 13 people at once or Christopher Nolan's Batman successfully engaging multiple firearm wielding thugs, if you attempt to fight more than one person at a time you will most probably get beaten down, no matter what color belt you possess. This is specially true when dealing with drunken violent sort of people because even if you hit them they often do not feel as much pain because of intoxication. In these cases it is better to avoid any altercation altogether until and unless they really threaten your life. The only way would be to kick them hard and fast at their groin or knees and run away quickly.
Do not allow your training to override good sense!
Always try to avoid fighting with anyone and try to dissuade violent and unreasonable people with calm and polite behavior. Do not give them any reason to be offended. Even if it is not your fault, apologize and move away from the spot. If this does not work threaten to call the police and send them to jail. Finally if all else fails then better run away while you still have the chance. If they grab and fight you then fight like a wildcat, use anything and everything you can to finish the fight.