
First thing first, you need to learn about your feet. There are two ways you can learn about your feet. The first is to take the "wet test" to determine what kind of foot you have, such as high-arched as opposed to flat. The second is to look at the wear pattern on the souls of your shoes. Knowing something about what type of foot you have before you head to the running shoe store can at least steer you toward a range of models with the specific technology to address your potential problems.
Wet test: Tracking your footprintsTo complete the "wet-test" simply wet the bottom of one foot and then step firmly onto a flat surface (tile or sand works). If you have a flat foot, you'll leave a fat, complete footprint. If your footprint appears almost severed in half vertically, so that virtually no print from your arch is visible, then you have a high arch. A so-called normal foot is somewhere in between: The footprint will show about half of the arch. The image on the right shows some wet-prints.
By examining the wear patterns (the places on your shoes worn smooth by repetitive use) of your old shoes, you may get some clues about particular models that will fit you best. From looking at the bottom of your shoe you will be able to figure out your pronation (see image on your left). Pronation in itself is not a bad thing because it helps your feet and legs absorb shock. However, excessive pronation (rolling in too much) can cause increased injury risks. That's called overpronation, and the answer to it is finding a shoe with good motion-controlproperties.
Runners with flat feet (and those with bowed legs) tend to be prime candidates for overpronation woes. A much less frequent problem is underpronation. Although they're a rare breed, underpronators tend to have an inflexible foot (and often a high arch, too), and when they land, their feet don't make much of a rolling-in motion. The result is a lot of pounding force. A runner that lands like a ton of bricks and underpronates definitely requires a shoe with plenty of cushioning to absorb the shock.
Most brands today offer a wide range of shoe types, so if you hear someone say "Nikes are better for high aches" or "New Balance are for flat footed people", this isn't true, it all depends on the style of shoe and most brands now make several styles. Words like "motion control" or "flexible" can tell you a lot about a shoe and shouldn't be over looked. As a sales representative to help you with any shoe language that you come across while shopping that you do not understand.
Finally, put it all together to find the right shoe for you. Once you know about your feet and able shoes, putting it all together is pretty simple:
For flat feet and overpronators- Look for the keywords "motion control" and "stability" when shopping for running shoes.
For high arched and underpronatings- Look for the keywords "flexible" or "cushioned" when shopping for running shoes.
For normal or medium feet- Choose from a wide variety of shoes including shoes made for normal feet, shoes made for slightly flatfooted feet, or shoes made for slightly high-arched feet. You don't want to get anything that mentions it has a lot of stability/motion control. You are also less likely to get injured, unless you pick a shoe that is counteracting your normal foot.
If you are running primarily on grass, trails, or any surface that is slippery, you may want to consider getting trail shoes. These shoes usually have added traction, durability, and stability; these shoes will help you get through the mud and leaves and, somewhat, the water with less slipping and sliding. If you run trails a large portion of the time, you may want to consider trail running shoes. However, it's always a good idea to keep a regular pair of running shoes around for when you want to hit the roads.
If you are a competitive racer you may want to invest in a good pair of racing flats. These shoes are made to be fast and flexible, but do increase the risk of injury. These shoes should only be used DURING races, and to break them in.
eHow has a great article on how to select a running shoe. Same for Active.com: finding the perfect running shoe...for you