I don't want to butt in about needle turn but if you have any questions about it, I'd be happy to try and help. I teach a needle turn class locally and am working on a pretty ornate applique quilt at the moment.
True needle turn does not use glue and pinning should be kept to a minimum. You need a very fine line drawn on the background fabric to guide where the fabric gets turned under and my secret..... drum roll please..... is to use a wooden toothpick to turn under your fabric. Dampen it in your mouth. That causes the wood grain to lift up and catch the fabric easily. Take teeny tiny stitches and only work on short spaces at a time. I do stuff some of the flower petals with thin batting. I don't cut the back of the quilt top to stuff.
If you have any questions, PM me. I'm always happy to help out a new applique quilter. Here's a picture of one of my applique blocks that I'm working on right now. There are 40 different blocks in this quilt, 8"x8", some with 80+ pieces.