I have put them in a corner (sometimes even making the label a triangle by folding a square in half and sewing it on with the machine when I sew the binding on and then I only have 1 side to hand sew), centered on the bottom, or pieced into the backing and quilted on. I love to use old lacy hankies that I embroider on my machine for my labels - do have to stabilize them. I'll use 1/4 or 1/2 of the hankie usually, sometimes I'll use the whole hankie, but only if it is quite small.