The two main factors in raw edge applique are the fuse able and the size of the needle and the thread. I use Heat n Bond light. It doesn't just make the back fuse able, it helps to bond the threads of the fabric together where Wonder Under doesn't do that so much. The other thing is if you're going to sew really close to the edge a smaller needle works best. I use a 60/8 microtex. Definitely nothing bigger than a 70. And never a Universal needle.