Sanding sides to a uniform thicknessthe sides, or ribs, of full-size guitars are all sanded to a uniform thickness of 0.085 inches. If a guitar is scheduled for a cutaway, that part is sanded to .075 inches to make bending the sharp curve a little less risky.
Before sanding the sides, I usually joint the edges that will touch the soundboard. The straight edge helps me align the sides in the form later on. I don't bother jointing or profiling the opposite edge. I do that just before gluing the back on.