I just got one of those quilt tacker thingies "Basting gun" (like the old "buttoneer") that shoots short plastic tabs through the sandwitch like the tagging guns for clothing. I just basted a small quilt with it, but haven't quilted the quilt and removed the tacks, so I don't know how it's going to look finished. However, it was easier than pinning and I don't have to baste.
If I don't baste or do something, my quilt backs get folds in them. I machine quilt on my regular sewing machine. I've tried fusible batting (works well, but it's 100% poly and pretty stiff), and spray basting (which messes up my floor if I do it inside, and there's also the fumes to deal with, or I have pollen/dust issues if I try it outside). None of these have been ideal. If I pin, I wind up stabbing myself more than once and then I have blood to clean off the fabric.