Quilting with a walking foot is limited to straight lines. For curved patterns, including hand quilters' fancy designs, use a darning foot. This foot jumps up and down as the needle raises and lowers, allowing you to move the fabric freely while the needle is up, but holding the layers flat and compressed when the needle is taking a stitch.
Drop or cover the feed dogs. You will manually control the stitch length, direction, and speed the fabric moves.
For practice, layer a piece of thin cotton batting between two pieces of muslin. Bring the bobbin thread to the surface of the fabric and hold both threads as you begin to stitch. When you press on the foot control, however, the fabric will stand still. You need to manually move it in the direction you wish to go. The speed you run the machine combined with the speed you move the fabric creates your stitch length. Practice to get a feel for this and to develop a consistent stitch length.
In the beginning, move the fabric slowly while running the machine at a medium-fast speed. Try to develop a rhythm with the motor while making scribbles on the fabric. Rather than turn the fabric, glide it in the direction it needs to go. Practice locking your stitches by moving the fabric very slowly, which creates minute stitches, for about 1/4". This should be done at the beginning and end of every quilting line. Once you've practiced for a while, select a small project to machine-quilt. A print fabric top will camouflage small glitches. Outline, echo, and stippling are good first project patterns. Stippling is a meandering, all over technique involving lines that do not touch, do not cross, do not have points, and are consistently spaced. Look beyond the hole in the darning foot and watch where you've been and where you are going.
Fancier patterns, such as feathers and cables, require advance planning to minimize the number of endings. When you're ready to tackle those patterns, stop at a quilt shop for a reference book.