The width of the strip i cut is determined by my desire at the time. Some quilts i want the binding to be brely visible, so I cut 1 1/2- 1 3/4 in strip fold in half legthwise, sew with a 1/4 seam to the front , turn to back and hand stitch down. If I want the binding to stand out, i decide how much, multply by 2. I then sew where I wanted the binding to show on the front.
You want your binding to have quilt between the layers, not just extra fabric at the edges. (Been there, done that-don't-leran from my mistake)
You'll get the hang of it. I have faith in you.:)