WesternWilson

I can second, third and fourth that table basting method (using baseboards you roll the quilt top and back onto) by Sharon Schamber. I can't crawl around on the floor or baste with safety pins thanks to arthritis, and her method is fantastic: you sit down at a table and can leave the project safely if you get called away.

I do not understand why this method is not more widely used!!
https://www.youtube.com/watch?v=zMP4iSeYAy4

Mkotch

I use a double bed for lap-sized quilts. I iron the back and use spray starch or sizing to insure that it isn't wrinkly in any way, Then I pin the back to the bed covering (quilt or bedspread) only at the top edge and smooth out the rest of the back before adding backing and top. I slide an old cutting mat underneath, starting at the center and pin baste there. I do move the mat around underneath until I have the whole thing pinned. For bigger quilts, I usually use large tables at our historical society or public library.