Using a piece of acetate to experiment with line
Using a large piece of acetate and a dry erase marker I sketch my ideas onto the acetate directly over the quilt. If I don't like the first pattern I can simply wipe it dry and start again. The lines are fairly thick because I have yet to find a dry erase marker with a fine point (note to Sharpie...please develop this for me). Drawing the lines gives my hands and brain a trial run for the real deal.
Once I have decided what I want to do I mark a boundary for the pattern on the quilt with a chalk marker. My favorite of these is the one pictured here, it has a roller at the tip that makes a thin dotted line with chalk. You can get white, blue, yellow and pink chalk. I tend to stay with the white stuff. I'll often hang the acetate near my machine so that I can see it while stitching. I'll do this stitching in the morning when I am fresher.