I am currently working on the background grid work on this wall hanging I made several years ago. Grid work is one of my favorite quilting designs. There is no need for special stencils and it can be adapted to any size block easily by changing the spacing between the lines. Some use masking tape to follow, I like to use a mechanical pencil to lightly mark the lines using the quilting rulers that I use to cut fabric. I think if you are wanting to practice, this is a good pattern to use. I find myself counting the stitches between the lines and it helps me keep my stitches even.
I would love to see your favorite background quilting designs.