I use the serpentine stitch and let it meander over the seam lines. I have also used other stitches for the quilting. I like to widen and elongate the stitches, if they are too small they want to sink in and the design can start to disappear. Really intricate stitches don't work as well as more open ones. I use my regular foot when sewing these, as some walking feet cannot be used in reverse, and some of these stitches sew forward and backward. I just go slow and easy and have not had any problem with using a regular foot.
Make up a small quilt sandwich and practice with different stitches, varying their widths and lengths. Use a permanent pen to mark the settings next to them for future reference :D:D:D