Flat-felled Seam (and 2 alternatives)

Step 2 Stitch seam as usual

The first step in any of the versions is to stitch the seam to be felled, right sides together, as usual. Use a 5/8th inch seam allowance (this is standard on home sewing patterns) and regular thread.

Stitch as precisely as you can, for best results. This is pretty easy on denim which is stiff enough that it does not shift as you sew.