I use washable school glue to baste my quilts. By doing this I lay down the bat first and then the back over that. Fold back the back half way and squiggle the glue around on the batting. All you need is a thin stream in a zig zag pattern for it to hold. I then smooth my back over the bat. I put the glue on the batting for two reasons: first so it doesn't soak through the fabric onto my surface and secondly it is heavier than the fabric so it doesn't move around and wrinkle like fabric does as you're working with it.
I let the glued area sit for a bit and then move the whole thing to another area that needs gluing, fold the back back, glue the batting and smooth the back over it. When this is completely dry I flip it over and do the same for the front of the quilt. I never have any puckers or wrinkles this way.
I had to piece a back recently with a contrasting fabric since I didn't have enough of the fabric I had planned for the backing. I wanted it to be perfectly straight with the front as it would show up once I quilted it if the pieced part seam line was not straight. I sandwiched the back on like above and then taped straws along along the seam line with some painters tape. The straws created a hump so I could feel where the seam line was when I flipped the back/batting over and then lined my top up with that straight. It worked wonderfully and when I quilted the quilt the straight line quilting lines lined up perfectly distance wise from the pieced part. A trick I learned somewhere but can't remember where but thought I'd pass it along.