As someone who has (and had) no idea how to applique, I found using basic shapes the best. Then fused each shape, one at a time, on the quilt to zig zag around.
Here are my applique quilts-the first one I did is at the bottom and is the simple sail boat quilt.
Corners were a challenge. Also finding the lightest weight fusable (I am limited on what I can buy locally). I did use 505 spray at times. I drew up the image or used a coloring book image (outline image), but maybe getting a applique pattern with simple directions would be best for the first time so you know which piece to place first.
Instead of a pattern, I just decided what I wanted and jumped in. Sometimes its better not to know what you are getting yourself into because you might not try it.
I say, GO for it! Have fun and have a good seam ripper handy.
I just looked at your applique quilts and they are beautiful! I love the same one that you cat does, the one with the Turtle.