The right shoe
You can make a preliminary judgment about your foot by looking at the shoes that you wear most often. Find a pair of your favorite shoes. They don't have to be running shoes. A pair of shoes that you have worn long enough for the wear pattern on the bottom of the shoes to be visible will do. Set the shoes on a flat surface so that you can inspect them from behind. Look carefully at the wear pattern, especially in the heel.
If all of your shoes are worn slightly on the outside of the heel and the inside of the sole, chances are that your foot pronates normally. If the heels of your shoes are worn badly on the inside but not on the outside, it's likely that you are an overpronator. If the outsides of your heels and soles are worn, you are probably a supinator.
You can also take the wet-foot test if you want more information. With the bottoms of your feet wet (but not soaked), step onto a piece of paper. If the imprint of your foot looks like a foot, you probably pronate normally. If the imprint looks like one large blob, you probably have flat feet and may need motion-control shoes. If you see separate marks for your heel and the ball of your foot, with nothing connecting them, chances are you have high arches and may be able to run comfortably in stable or cushioned shoes.
Once you've determined what kind of foot you have, the next step is to buy a pair of shoes that are appropriate for your foot. It's not really all that complicated.
Motion-control shoes do exactly what they say they do. These shoes are designed to prevent the foot from rolling inward. This is accomplished by using different materials or placing devices in the sole of the shoe. If you overpronate - that is, if your foot rolls inward too much - a motion-control shoe can help. These shoes tend to be rather stiff and generally don't have much cushioning. Runners with flat feet often do well in motion-control shoes.
Stability shoes have more cushioning than motion-control shoes but are still designed to prevent excessive pronation. These shoes usually provide support for the inner (medial) part of the foot. Runners with normal feet, or those who pronate just a little too much, do well in stability shoes. Cushioned shoes feel the softest when you run. They may feel so wonderful that you think you are running on clouds, but they provide little or no support and don't control foot motion at all. These shoes work best for the biomechanically blessed runner who does not overpronate or oversupinate. Unfortunately, the very softness of cushioned shoes can lead to problems. If the foot rolls inward or outward too much, a cushioned shoe won't do anything to prevent the excessive roll. Even though they feel great at first, shoes that are too soft can lead to pain in the knees as your joints struggle to keep the foot from rolling inward or outward. Since so few runners supinate, or roll to the outside of the foot, there aren't nearly as many shoe choices for this type of foot. If you supinate, you will want to avoid shoes designed to prevent the foot from rolling in, because they will just make your problem worse. Look for shoes that enhance the foot's natural tendency to roll inward.
The importance of wearing shoes that fit properly cannot be overemphasized. Typically, your running shoes will be a half to a full size larger than your dress shoes, but time is very little consistency in sizing among brands of running shoes. You may wear a size nine in one model, an eight and a half in another, and a nine and a half in still another. The sizing is even less consistent between shoe manufacturers. Forget the size. Buy the shoe that fits.
A good rule of thumb is the rule of thumb. When you are standing, you should have a space the width of your thumb between the end of your longest toe and the end of your shoe. Always remember that it's much better to wear a running shoe that's a little too long than one that is a little to short. You can always buy thicker socks, which provide more cushion, if the shoe is a bit too 1ong.
Modern running shoes are far superior to the gym shoes of childhood. By using a little common sense, you can make your first or next shoe-buying experience much more pleasant. With a little practice, you'll find that you're able to use words like overpronation and medial support along with the experts.
Most cities have running specialty stores with qualified sale people who will help you select the best shoe for your feet. Often these stores are owned and staffed by runners. Although you may intimidated at first, they really are there to help you become a runner. If you find a store with staff who don't want to help a new runner, use your old shoes to walk to a different store!