Whichever method you use, the binding should be filled with batting and fabric to the fold. This makes the binding stronger.
On miniature size quilts, I use a single thickness and cut it 1 1/4" wide. Then it finishes 1/4" wide.
On small to medium size quilts I use 2 1/2" wide binding, folded in half. I place it 1/8" from the cut edge of the quilt and stitch it 3/8" from the cut edge. On the back I glue it down to fully cover the stitching line. Then stitch in the ditch from the front on the machine.