A leather sole
There are some well made brands out there that do not have leather soles but usually this feature is an indication that the items are made of higher quality materials. Brands that use leather soles over man made materials also tend to have more stringent manufacturing processes which contribute to a better shoe. In addition, shoes with leather soles can be resoled when well worn which means that those $200 heels could last for years and years for a minimal maintenance cost. This does not apply to athletic shoes. Those are a whole different story.
Well made hardware
Take a very close look at the buckles, notions, or other hardware on the shoes. Does the metal have casting lines or rough edges? If there are rhinestones are they clear and set properly? Are the notions stitched on well? Or is the work sloppy? A flaw in the hardware and haphazard application of it is a sign that the shoe was put together with cheap materials and made quickly. It is unlikely that a pair with these signs will last for long.
Durable upper material
Leather shoes are by far the most durable materials for uppers. As long as it is conditioned and taken care of properly, leather shoes can last for years. Man made materials and fabrics have less durability and require a lot more care. If the material looks very plastic like or the fabric too thin it is probably best to stay away.
Check out the insoles
The best shoes will not only look great on the outside they will also look great on the inside. The insoles should fit well with no gaps and be secure. Very good shoes will have some slight cushion and the insoles will be made of leather too. Leather insoles breathe and prevent sweaty feet and stinky shoes.