I've tried a few different ways to baste ...
I liked spray basting for small pieces only. I had such a problem with positioning and overspray when I tried to spray baste a large quilt that I will never do that again.
For larger quilts I use Sharon Schamber's method where she uses two boards to help keep the top and bottom smooth (and it does a great job of doing that), and then I hand baste (even though I hate it). I do two things different than she does though. One is that I use water soluble thread so I don't have to pull all the threads out when I'm done quilting (I just quilt over them), and the other is that I baste with the backing on the top. The reason I baste with the backing on the top is that when you make the herringbone stitches - the stitches on the topside are larger than the stitches on the bottom side. Those long herringbone stitches are easy to catch on the hopping foot when quilting. So I baste with the backing up and that way the longer herringbone stitches are on the bottom where they won't be caught on anything, and the smaller horizontal stitches are easier to avoid when quilting.
The next quilt I do I think I'm going to try using elmers school glue. Not sure what method I'll use for keeping the backing/batting/top straight and smooth ... I'll work that out. I won't be able to use the boards.