Never be embarrassed to enter a quilt in a show. I entered my first try at applique in a local show. I though well if someone see it they may think if that can be entered I know my quilt can be too. LOL The judge was critical of my stitching but loved the design and color. I was okay with that. Seeing the quilt hung with all the other quilt made it look much nicer then I could see it. For advance applique classes your best bet would be at a big quilt show like Houston, or any AQS shows. Zoom classes are wonderful if you can't travel.
Honestly I don't think there is any trick to sewing excellent applique. Learn the basic steps, do a lot of applique, and be comfortable with making mistakes.