Myself, I suck at applique. However, I've had two different friends/quilt group members who were masters of their craft and were willing to give me pointers and help for my limited efforts. One had a more modern pictorial style and used invisible nylon-type thread and the teeniest stitches by machine. The other did hand applique of all styles but was particularly fond of the more folk art/primitive style. She could do either big stitch or close to invisible and preferred to work with silk thread. Both of them won many awards and were self taught and believed in practice practice practice.
In addition to just asking/hanging out with people better than you, I think looking close at winning quilts can teach you a lot on how to do good curves, how to end lines etc. Of course, if you get a chance to take a class by a master that helps too, but not all of us are geographically or monetarily blessed.