Stitching in the ditch can be tricky too. When I started, I used a sort of zig-zag. . . . not the kind that was one stitch to the left and one to the right, but three to the left and three to the right. Most machines have this stitch. It is very forgiving. Then you can follow the seam lines with that, or go diagonally from corner to corner(s). Then if you don't stitch completely straight lines, it doesn't show.