These instructions:
https://web.archive.org/web/20121103040713/https://chefonabicycle.com/2012/10/28/how-to-correctly-patch-a-tube/
seem pretty good. My procedure isn't too different. They use a dedicated stitching tool to press the patch and tube together. When I'm at home I've been using the edge of the cement can, which seems to work ok.

I still don't have a good substitute for a stitching tool on the road. What do you use?