Shoe fit is subject that you can look up that is about a exciting as the laitest tax expentions.

First Measure both Feet with a brannock device (that metal thing that is in most shoe stores).

Instuctions.
brannock.com/cgi-bin/start.cgi/brannock/instructions.html

One foot will be often larger than the other. Fit the larger foot first. You should have a thumbs width distance from the end of your longest toe to the end of the shoe.

If their is greater than a size defference between feet you may benifit from two different size shoes.

If you are trying on a shoe that is the correct size and it does not stay on youf foot you need to wear a different style of shoe.

Typicaly a slip on shoe needs to be 1 to 1 1/2 sizes to small to stay on you foot. Then I will see people who will use this reduced size to fit their running shoe and that can lcause many foot problems.

Heels it is typical for most shoe to have a 3/8 inch heel. when youe wear a shoe with a heel greater than an 1 1/2 inchs you put the foot an ankle in a unstable possition which can be be bad for the knee and back. Like many things that are bad for you it can take years for the damage to you body to become noticable.

So hopfuly this will spark some sort of discution that might be of interest.