I have 4 basic patterns I generally use in borders, although I do use others. The easiest is stars. These are just like what your primary teacher may have used on your papers, with short connecting lines.
I also do vines with leaves, which is much easier than it sounds, serpentine feathers and ocean waves. I do all of these with an embroidery foot. Try it first on a potholder, not your precious quilt. It varies with machines, but you will probably have to lower or cover your feed dogs then drop your stitch length to zero (YOU will be determining the actual stitch length.) Do not try to go fast.
I found out early on that just SID on borders generally results in a wobbly border, as the border will be longer than the body. If you want to do only straight stitcing, I suggest that some of the stitching go across the borders.