I use my cutting table. Start in the center of the quilt with backing wrong side up and use binder clips to hold that to the table. Next is the batting which, when smoothed out, I clamp that down with the binder clips. Next the quilt top right side up and clamp that with the binder clips. I usually pin baste with pins about a hand-width apart in all directions. If it's a really large (queen/king) I might thread baste to reduce weight but use the same distances. Again, if it's a large quilt, once I get the center section done on my table, I'll shift the whole thing up/down/left/right until I get it all basted. The binder clips are the cats meow for me.