I do them basically the same as Gina -- cut a square an inch larger than the unfinished size I want ... cut on the diagonal, sew them, set the stitches, iron the seam open (finished pieces lies a LOT flatter) then square them up. Yes, there's a little waste, but my HST's are perfect. Every single time. When I tried to draw a line first I found many times my squares were no longer square! I now avoid ANY technique that requires me to draw a line on the fabric if at all possible.