I make these all the time and I place my straps 16" down from the top and have six inches between the straps which leaves lots to cover the seat in all directions. I make my straps 1 1/2" or 2" wide and use velcro to hold them on. Every mother that I give them to loves them and I like them because they make a little tent over the baby, keeping out the cold air but not restricting breathing in any way.