I was taught, and continue to practice relaxed tautness in bagua. When you stand and fully extend your arm, you feel a spot where it almost buzzes at the end of the fingertips. The body is relaxed, but the soft tissue if fully extended. This feeling of tautness is maintained throughout the movements. While in the beginning, one needs to fully extend the limb to achieve this quality, as you become more adept at internal workings you can carry this feeling of tautness without showing it outwardly.
Others will probably have a different answer to your question, but this is mine, FWIW.
Also, when coming back towards the center of the circle during the palm change, focus on maintaining your structure (think peng) with the outside hand, leading with this hand, not the one closest to the center of the circle.
The more one sweats in times of peace, the less one bleeds in times of war.