One of the things you can do is to look to Free Motion Quilting (FMQ) designs and see if you can adapt the designs to quilting with your walking foot. One of the easiest FMQ designs is the “continuous curve.” It can also be done quite easily with your walking foot with a few modifications.
B & C) If we adapt this design to be quilted in rows and columns this design becomes super easy! You will basically alternate 2 long wavy lines. First you stitch a wave like in “Fig. B” Notice that this curve starts with a “hill” then a “valley” and then repeats. The next step is to stitch a wave like in “Fig. C” that starts at the same point as your first wave. The image doesn’t show them starting at the same spot, this was on purpose so that it would be easy to see the differences. Notice that curve “C” starts with a “valley” then a “hill” and so on. It’s basically the opposite of curve “B.”
You can quilt all of your “B” waves, then all of your “C” waves. Then rotate your quilt 90 degrees and do the vertical waves.
Not as complicated as it looks is it?