I've read this answer some time ago, but can't find the answer now. There is a order in which you test the water, and also a order in which you correct the balances. What are those two orders.
What's most important is a full set of TF 100 results. From there our experts will tell you what to do first. That will depend on the results to some extent depending on which tests are out of desirable range the most.
What's important is that you test everything before you make any massive adjustments. For instance, if FC is 15, your pH reading will be wrong. So you don't want to just test pH and then rush off to dump acid in. You also need TA to use poolmath properly for pH adjustments, so that has to be done but again if FC is too high, the colors will be skewed.
I dip out a plastic cup of pool water and carry it off to the patio table to do all my testing while seated comfortably, not squatting poolside.