Deciding you want to take up a martial art as a hobby can leave you with other questions. What style of art do you want to learn? Why do you want to learn? Most importantly, where will you train. Most major cities and small towns have establishments where you can learn martial arts, but you may not have access to a training center due to distance or lack of funding. Does this mean you should give up on the thought of learning a martial art? Not necessarily, because after all, these arts came into existence hundreds or thousands of years ago and underwent refinement over time. You have a few options available to you if you want to learn the basics. Training entirely on your own is possible to an extent, but not as effective as formal instruction.
For starters, try shopping for martial arts instructional DVDs or in the local library for books about the martial art of your choice. These training aids provide photographs and full video demonstrations of martial arts techniques, with the tutor or instructor providing additional explanation. Some books, such as "The Tao of Jeet Kune Do" by Bruce Lee, offer thorough advice. You cannot, however, learn martial arts simply by watching someone else practice. You have to train along with the instructions to get the most benefit. Don't try to rush through the course just to get to the next technique or section; the majority of martial arts curricula are about repetition of technique to ingrain the proper motions into muscle memory. It's likely that you will develop improper form and poor training habits, so you have to pay careful attention to your movements.
You need training equipment and a clear space in which to work. You can purchase a uniform, but if you're short on money you can use ordinary workout clothing provided it's loose and light. Allow yourself approximately 100 square feet; this should give you ample room to practice kata, or forms. If you're learning a grappling art such as aikido, you need something to cushion against falls. Traditional Japanese schools used tatami, or rice mats, for this purpose. A gymnastics mat works well, or you could use a mattress - just make sure no springs are protruding.
When you have your training equipment, you should devise a daily workout regimen. All martial arts warmups begin by stretching muscles; injuries can easily occur otherwise. After stretching, martial arts classes involve a review of the lessons learned in the previous class. Techniques tend to build on one another, so ensure that you take time to review and practice what you already know before incorporating any new knowledge.
Sparring, or the use of techniques in mock combat, is an essential element of martial arts training. You may be able to find a partner to train with you, but you should never attempt complete free-form sparring without safety equipment such as helmets and pads. Instead, focus on several-step sparring, which involves a set exchange of movements similar to a form.
With care and patience, you can learn some martial arts principles on your own. However, you should seek formal instruction if your location and finances allow.