There are so many variables when it comes to selecting the right string to play with. From personal experience, I feel it is most important to not be bias when deciding on your string of choice and to also remain open minded.
I began playing with absolutely no knowledge of the equipment I was using. After nearly two decades in the sport, that has changed. Here are some tips on how to select the right string for you;
1. Select 2-3 brands you are interested in and ignore the rest (initially).
2. Select one type (for example, polyester or synthetic gut) of string to use from each brand and restring the exact same racket, using the same tension for each string. This will ensure that the test is controlled.
3. Number your rackets and make note of the type of string in each frame (I would place some tape over this number so you aren’t bias in your selection).
4. Alternate from one racket to the other every 5 minutes in practice, so you can feel the difference in the way the string plays immediately.
5. Ensure that you play every shot that you would usually play, so your groundstrokes, volleys, serve etc.
I hope these tips will help you when you are trying to find the right string.