Applique is not one of my strong skills -- but there are some things I will do from time to time, so I know there are different ways to do things.
So might get more pertinent help with what sort of patterns or designs you want to work with.
For me, I usually have large shapes and do the technique where I draw on one-sided light weight fusing, and then sew in tiny machine stitches around the boundary. You cut a slit in the interfacing and turn the fabric right side out, the seams folded in and then the whole thing gets fused in place.
But I have friends who are absolute masters with the turning the edges, or the finish stitching the raw edges, or other styles.