Everyone has a different shape to their foot. Some people have a high arches and some people of no arches. Regardless of what your genetic makeup is of your feet, finding the correct running shoe is very vital to your foot strike.
Most of us walk/run with a neutral stride, meaning when we propel our bodies forward we utilize a heel to ball foot strike. So your heel will touch the ground first and your weight is then evenly spread among st your foot in a rolling type of movement. The problem arises when this rolling action is either to far in wards making you over pronate or to far out wards making you under pronate. If you are walking/running with a shoe that is not designed for your type of heel to ball strike then you may suffer from hip, knee, and ankle pain. Not to mention, this may throw your lower extremities out of alignment.
The best solution is to find a good running store that can analyze your gait, which is your pattern of movement. In most cases over pronaters may need a shoe with a more straight last, and underpronaters perform better with a semi-curved last shoe. These are merely suggestions and it is best to have your feet examined by a doctor or podiatrist to truly understand the mechanics of your feet.
For those of us who don't have time to go to a doctor, here are a few great running shoe stores in and around Los Angeles.