These are my favorite methods. We were give instructions to watch these prior to a class project involving inside and outside corners. I linked them all so you can choose the one you want.
https://quiltwithmarcibaker.com/quilt-videos/
You want to make sure the corners are folded with a 45 degree. Sometimes I lay the binding on the cutting mat to get the true angle.
ETA: The stitch off in the corner really helps too and worth the effort.