You do NOT want two straps and have the quiver sit straight up as the arrows will rattle too much. You want a single strap that allows you to slide the quiver under your arm as you duck under low hanging limbs as in this photo....
You want the quiver to be stiff enough to hold shape, but broken in enough to conform gently to your body.....like this.....
You want the nocks near to your ear--as a lefty I like for the strap to be centered at the top but angled to the side at the bottom....like this.
If a quiver is made from leather that will gently mold to your back, lets the arrows hang so they lay sort of on top of each other, they will ride quietly, not fall out when you lean over, will not need any sort of stuffing like rice, oats, etc. in the bottom. A piece of old carpet cut to fit the bottom of my quiver is all I ever use. The long thongs attached to my quiver allow me to tie on a shirt or other item as the day warms up or maybe fletch cover, a rain jacket, poncho, etc.