The National Institutes of Health (NIH) has a nice article on foot care. Some pointers it gives on selecting shoes are:
REI also has nice articles on selecting hiking shoes or boots, caring for the shoes/boots, and selecting hiking socks.
- Shoe size may change as you age, so always have your feet measured before buying shoes. The best time to measure your feet is at the end of the day when your feet are largest.
- Most of us have one foot that is larger than the other. Make sure your shoes fit your larger foot.
- Don't buy shoes without trying them on first. Shoe sizes can vary depending on the kind, make, and style. For example, the size you wear for sneakers may not be the same size you need for dress shoes.
- Walk in the shoes to make sure they feel right. The heel of the shoe should not slide up and down when you walk.
- Choose a shoe that is shaped like your foot. Styles with high heels or pointed toes can hurt your feet.
- Stand up when trying on shoes to make sure there is about 1/2 inch between your toe and the end of the shoe.
- Make sure the ball of your foot fits comfortably into the widest part of the shoe.
- Don't buy shoes that feel too tight and hope they will stretch.
- The upper part of the shoes should be made of a soft, flexible material.
- Soles should give solid footing and not slip. Thick soles cushion your feet when walking on hard surfaces.
- Low-heeled shoes are more comfortable, safer, and less damaging than high-heeled shoes.
I've found that light-weight or mid-weight hiking socks generally make good socks for wearing with dress shoes/loafers (for those of you working in an office environment), and you can generally find them in dark colors to go with a suit or slacks.
Although I have issues with their long term durability, I like the EcoSox hiking socks made with bamboo because of their wicking and odor control. However, at least for me, they tend to unravel at the toes or ankles fairly quickly (perhaps I pull on them too hard?). My son, though, seems to have had better luck with them.
Update (Oct. 11, 2017): "5 Best Hiking Socks"--Back o' Beyond. The author gives his opinions based on experience and testing.