When I made my first quiver I decided to have adjustable straps, so I could try out where it would fit me the best.
Step 1: Holes and Chicago Screws
I punched four holes on the upper back side and four holes on the lower back side. I used chicago screws so I can remove the lower strap when I have the quiver on my hip.
Step 2: Short Straps, Measure Calve and Ankle
I measured my calve and ankle for the short straps. Most of the weight (altough quivers are very light) rests on the ankle.
Step 3: Longer Straps
Take help from a friend and have them put the quiver on your back, hip, thigh or wherever you want it. Then measure and make long straps.
When you're done with the long straps, simply attach them to the shorter ones.
Fyi, if you use a metal buckle it can be a little bit uncomfortable. Use some sort of padding if you can't handle it!