To heavily starch yardage, I mix a 1:1 solution of Sta-Flo liquid laundry starch and water, "paint" this solution onto the fabric using a large wall painting brush until the fabric is saturated, wait a couple of minutes to make sure the starch penetrates the fibers, toss in dryer, then iron with steam. This is what I do for quilt backings and flannel (that I plan to piece), as it creates a very stiff and stable fabric.
I do not prewash fabrics for my quilt tops and find there is enough starch/sizing in them to make for accurate cuts. I use spray starch as I create blocks and strip sets, to add stability as I go.
Sizing does not stabilize as much as starch, so starch remains my favorite.