For starters, you could buy shoes from a podiatrist or pedorthist. We are specialized in getting you the perfect match for your foot type and activity. If you do go to a shoe store, be sure the salesman measures both feet with a foot measure.
Also, shop for shoes in the afternoon or evening. Your feet will swell throughout the day so trying shoes on in the afternoon or later in the day will help to make sure they will fit on a regular day. In addition, after you have been wearing the shoes. Make sure the wear patterns are consistent, you don't want a certain part of the shoes to wear out before other parts, this may mean they do not fit properly.
If the shoe slides up and down, squeezes in any area, or your toes touch the front- these are simple signs the shoes do not fit. Your shoes should not require a "break in" period. They should feel great from the start!
In order to make sure you get the best fitting shoe every time, get measured by a professional!