I stretch out and tape the sheet to the floor. I just spread the back onto the sheet. Kinda of hand press it smooth, I don't pin or tape the back to the sheet. The fabric to fabric keeps it in place. Then add next layer, hand smooth out, then the top, hand smooth out. I usually pull back half the batting and top (together), spray baste and work it back into place, starting at the middle working to end/edge. Turn around and do the other side. Then repeat and do the top. I have done this for years and 90% of the time it works out.
Most of my lap/twin and smaller I spray baste. The larger one go to the quilter.