Here's a good way to discover a great beauty salon: find someone whose hairstyle, manicure, and the like look great, and ask them where they get theirs done. If they're willing to point you in the right direction, they may even get you an "in" to the salon -- a necessity if it's particularly popular.
The atmosphere of a beauty salon can be a crucial element in its selection. Does it feel peaceful, or is it buzzing with energy and a little stressful? Most of us would elect for the more peaceful shop, but the one you prefer may depend upon your own personality.