As I have not yet tackled the challenge of freemotion quilting I do diagonal lines on all mine with a walking foot. I have drawn with (supposedly) washable pencil, eyeballed it from corner to corner on square blocks, used painters tape, and most recently tried the hera tool. The hera is my favorite! I used it after I had sandwiched my quilt and basted with safety pins. It worked really well with my hars wood floors. I will try again - this time without the sandwich and hope for the same results. You'll be fine! Just baste well.