The Practice of the Right Style

There is (and has been for some time) a great debate about which style is the best. Each student is different and must find a martial art that suits them, but here are some things to consider:
Some styles of martial arts focus on high kicks, some focus on strength of the fingers, and some focus on keeping low stances. Obviously, or at least obvious to me, the type of person you are has a lot to do with how successful you might be in a given style. Someone with arthritis may not be able to give the high kicks necessary to practice certain disciplines. Someone who has bad knees may not be able to maintain a low stance for very long. Some people may even have an ethical problem with the moves used in the style. Whatever the reason, some people just aren't cut out for some styles of martial arts.
When finding the right martial art for you, consider your body type and composition. If you feel strongly about a martial art and want to practice it despite some naturally occurring obstacles, go for it! Most instructors are willing to help if you make the effort. However, it may be best to start with something that won't be an uphill battle all the way.
Next, it is important that you dedicate yourself fully to the martial art you settle on. Don't try to take on a number of martial arts at once - you may confuse yourself, you may injure yourself or others, and you may not be able to dedicate the focus needed to become truly proficient at any style you're doing. The idea that if you practice a year of karate, a year of judo, a year of kung fu and a year of tai chi you will be a well-rounded practitioner is also false; you will become a "jack of all styles, and master of none."
I do, however, encourage you, once you have been in the same style for at least five years, to branch out and try new things. Your expertise in one style will help you to learn others and will aid you in becoming a "renaissance" man or woman of the martial arts. I would recommend studying a hard style first, (tae kwon do, karate-do, kick-boxing, et cetera), transition into a hard and soft style (certain styles of kung fu, karate, hapkido, jujitsu, et cetera), and "finish" with a soft style like judo or aikido.
On a final note, finding the right martial art for you can be a big challenge, but add to that the challenge of finding a sensei or a teacher who is competent in teaching that martial art, which may be an even bigger one. Never "settle" on a teacher, doing so will only lead to improper technique, injury or worse. Make sure you love what you are doing and that you love the people you are with.