Dealing with the general public can be quite interesting especially if you are dealing with their feet. I find that there are many things in common that might help the average person find a better shoe for their walking and running needs. Let me give you some "rules to go by" when you are looking for a performance shoe.
First, let me tell you what I mean by a performance shoe. A performance shoe is a shoe that you a buy because you need a shoe to do a specific job albeit running/ walking or just standing on your feet all day. You must find a shoe that does the job and not buy a shoe because you like the color or style.
Performance running/walking shoes come in three basic categories, stability, cushioned or neutral and motion control. Now you want to find out what kind of foot you have so you can match your running or walking characteristics to a shoe that best works with your feet. You need to take off you shoes and have someone watch you walk to see if your feet are rolling in (pronating) or rolling out (supanating). If you are rolling in you generally need a stability shoe if you are rolling out you generally need a neutral or cushion shoe. if you have flat feet generally you should be looking for a motion control shoe. Width is also a consideration, most people can fit into the standard width shoe which is "B" width for women and "D" width for men. Most athletic shoe companies are making performance shoes in width now days so find a shoe that comfortable on you foot for both length and width.
Let me talk about some other things you should have in mind when you are going through this "find the right shoe process". Most running/walking shoes are going to be one full size bigger than your regular dress shoe. The reason for this size increase is, as you exercise you feet swell up a bit and you need to anticipate that. You also want to feel like you can "play the piano" with your toes inside the front part of the shoe called the toe box. The shoe should also fit snuggly on your heel. The shoe should have about a "thumb nail" distance from where you longest toe is and the end of the shoe, once again to address the swelling foot issue and to avoid black toenails.
Now that you have some good basic information about your foot and the type of shoe you might want go a store that stocks a good selection of several different performance shoe manufacturers. There are a lot of good shoes out there and price doesn't always dictate what is best for you foot. You should find a salesperson that can at least measure you foot and tell you the difference between a stability shoe and a neutral shoe. Try some styles on and go out of the store (if allowed, not shoplifting please) and run or walk in the shoe. There is very little "brake in" with performance shoes so what the shoes feel like in the store is what it is going feel like at home and through out its use.
Congratulations, now hopefully, you have shoes that feel great and let you enjoy all the benefits of the exercise your body needs. Remember though, the life of the shoe is only 300 to 500 miles or six months which ever comes first.