Take a tracing of your foot with you. Place any shoe you think you might buy on top of the tracing. If the shoe is narrower or shorter than the tracing, don't even try it on.
Shop for shoes during the afternoon — your foot naturally expands with use during the day.
Wear the same type of socks to the store that you intend to wear with the shoes.
Have a salesperson measure both of your feet — and get measured every time you buy new shoes. Feet change with age, often growing larger and wider. If one foot is larger than the other, buy a size that fits the larger foot.
Stand in the shoes. Press gently on the top of the shoe to make sure you have about a half-inch of space between your longest toe and the end of the shoe. This provides enough room for your foot to press forward as you walk. Wiggle your toes to make sure there's enough room.
Walk around in the shoes to determine how they feel. Is there enough room at the balls of the feet? Do the heels fit snugly, or do they pinch or slip off? Don't rationalize that the shoes just need to be "broken in." Find shoes that fit from the start.
Trust your own comfort level rather than a shoe's size or description. Sizes vary between manufacturers. And no matter how comfortable an advertisement claims those shoes are, you're the real judge.
Pay attention to width as well as length. If the ball of your foot feels compressed in a particular shoe, ask if it comes in a wider size. Buying shoes that are a half-size bigger — but not any wider — won't necessarily solve the problem.
Feel the inside of the shoes to see if they have any tags, seams, or other material that might irritate your foot.
Examine the soles. Are they sturdy enough to provide protection from sharp objects? Do they provide any cushioning? Take note of how they feel as you walk around the shoe store. Try to walk on hard surfaces as well as carpet to see how the shoe feels on both.