I can only see the superimposed lines in the imgur link. Did you intend to post an album, because I can only see one image in there? Regardless, I think you're looking too much into accuracy from the wobble of the lines alone with some frawying on the starting end of the lines. Take your time and be patient to place your pen on the starting point to avoid fraying on both sides. The important thing is creating a smooth, confident line, the accuracy of hitting the end points comes later