My edges are the thickest they've ever been, probably due to low manipulation. I never comb or brush them, and I stay away from styles that will break them. I wear my satin bonnet inside-out, so that the elastic won't pull at them, and when relaxing, I apply and smooth that area last, before rinsing.
To get my edges to lay down smoothly, I apply plain water and 100% aloe vera gel with my palms and tie down with a scarf. After about 15 minutes, VOILA!...smooth edges!