I'm going to try spray basting for the first time. I've always used pins before and started quilting in the middle and going out to keep the back from puckering.

Since this project will be spray basted can I start anywhere and quilt randomly in a block at the bottom, switch to a block at the top, then a block in the middle and back to the bottom? I might even mix up machine quilting with hand quilting. It would be helpful if I could work on whatever section that I wanted without having to worry about the back.

What would you recommend?

I use a mixture of pins and spray but I still quilt from the middle out or stitch in the ditch corner to corner first or vertically and horizontly. What I'm trying to say is that I don't think using the spray changes the way you should quilt it.

I have done both and always go from the middle to if just doing lines start with the center line and work out. just to be safe.

Heavy sigh...

I have used spray before and didn't really like it. I was quilting a wallhanging, 24" X 48" and much of it wasn't still basted by the time I got to the outside borders. I definitely pin all my quits now!!

If you are going to do any stitch in the ditch, to that first. That should hold enough so you can quilt wherever you want. Sometimes I use water soluble thread and baste a few lines each direction (after spray basting). When I do that, I can quilt anywhere I want and have not had any puckering issues. I don't quilt very tightly though, not sure if that would make a difference.

I just recently started using basting spray. I like it, but I still use pins, but not as many. I just don't trust it yet to hold well enough to keep up when I'm scrunching and pulling my quilt around for FMQ.
I do like it for small projects though.
I saw on a "Sewing with Nancy" video that she used fusible web for a quilt. Make a long thin *1/4" or so strip of fusible, then put at piece down every 5-6" or so and cut it off so only about 1/2" goes down.. Just use your iron on it and pull the extra tape against the edge to break it off. Then when you're ready to add the top, peal the paper off the tabs, and place your top on. Spot iron over the tabs and it holds as well as pinning.
Here's the link
http://www.wpt.org/sewingwithnancy/sewing.cfm
Advance it to the "letter Q" for the technique.

Oops, sorry, Q was on last week, but it's gone now. Or you can order her book.

Before I begin to quilt, I will iron the quilt from both sides to help get the wrinkles out. Of course, this depends on whether or not you have the space.

Ditto on both comments.

I like the Sullivan spray baste very well but still pin some,just in case. I have noticed if I use the basyting spray with poly batting it doesn't hold very well but the cotton batting is fine.