Hi Ray,
Brookwood leather has some great videos on how he does it.
Keep in mind the type of guitar you are making the strap for as well. The wider the strap, the more comfort you will have, especially for the Les Paul type guitars. Check out El Dorado straps for inspiration on tooled straps or classic style and then adapt for your own style. I am working on one for a acoustic guitar now.
Enjoy,
RC