As above....BUT (wait for it) make the tiny slit in the background BEFORE you add your applique piece....
I know right?!?!? Lol, I had been struggling with this one step of needleturn for 15yrs. One day I was demonstrating at a show, and this very old lady told me my technique sucked. I was a bit offended and asked what she meant, and she very offhandedly told me to slit the fabric a tiny bit FIRST, just enough to get the tip of my embroidery scissors in. Boy, did I feel small lol.