I usually have the backing about 4" larger than the top, and the batting about 3" larger than the top. That way I can see the backing with the batting centered on it. The backing is either clamped or taped down real taut. I mark the center of the bacling/batting with tape or a pin and fold the well-pressed top in quarters. Then I align the folded edge of the top along the center line of the backing/batting. I smooth the top down as I open it. Lastly, I pin about hand-width apart, trying not to place pins in my path of quilting.