Thread basting quilts is probably the most commonly used method for basting quilts. The three layers of the quilt need to be secured together while you are quilting and thread basting does the job admirably.
Begin in the middle of the quilt and sew long running stitches (basting stitches) towards the edge of the quilt, smoothing as you go.
When thread basting a smallish quilt, begin in the middle and baste a straight line up and down the middle of the quilt and across the middle. Then sew a line of basting stitches along each diagonal from the middle to the corner. This will give you eight lines of stitching in a star design.
When thread basting larger quilts, there needs to be more basting than the star above, or the layers may move against each other. In this case it is better to thread baste a grid of straight lines up and down and across the width of the quilt. The lines need to be no more than about 4″ apart.
When you have finished thread basting your quilt and feel ready to begin quilting, do take one final look at the back of your quilt. sometimes the backing fabric moves a little during the basting and may need straightening out.