If we are talking telltales then it would help if there was a guide to help you.
Arvel Gentry applied aeronautical engineering to create a guide to sail trim using telltales.
I'd like to do two things in the following discussion. First, help you establish your own systematic approach to trimming the sails. Second, help you learn what the different sail adjustments actually are doing to your sails.
Photo 1 shows the telltale system I use.
See the attached document