I do size the wood first but generally wash the back and the rawhide(and snake skins) with Dawn dish soap and warm water and rinse with boiling water. This not only cleans the wood oils and hand oils off the wood but also hydrates and breaks the surface tension of the wood so it accepts the glue. (ie. put a drop of water on a freshly sanded back and it will usually bead up(surface tension). After washing, that drop will be drawn in by the wood)I generally give it a couple of sizing coats waiting a few minutes between the two. Then I coat the rawhide(or skin) and the back with glue and lay the backing down. I like to work with 2 pieces of backing, starting at the handle and work out the limb. I like at least part of the backings to overlap at the handle, either by about 1" but mostly the whole handle area.
Once both pieces of backing are down I make sure that there are no air bubbles or glue pockets. If there are I try to squeeze the out the sides or make a small lengthwise razor cut to get them out. You'll never see the slits after the backing dries and it won't hurt the integrity of the backing going lengthwise.
Also, hide glue has "suck" which draws the backing to the bow's back as it cures which generally eliminates the use of a wrap but if I feel a wrap is necessary I only leave it of for about an hour. This is enough time for the glue to start curing but you still have iome to make corrections if needed.
