First, choose natural gut or soft synthetics. These strings usually play with less shock and vibration. Additionally, you should use the lowest possible string tension with which you can control the ball. Even a 3 or 4 pound reduction in tension can provide some relief. By all means, avoid all hybrid strings that contain Kevlar main strings.
Many players look for the longest lasting strings that they can find.
Cost and the inconvenience of having your racquet strung are usually the underlying reason for an emphasis upon durability. If you fall into this group, tournament nylon, synthetics and hybrids that contain Kevlar main strings are your best bet. When switching from one gauge string to another, it is important to make some tension adjustments. To get the same feel and power, I offer the following table of reference. In addition, I recommend that you keep a written record of when you last strung your racquets, what string type and gauge you used, and who strung the racquet.