Hi, Carolyn. When you hold the quarter round in place on the floor to measure it, make 2 marks on it. The first mark should be a tic to show the length of the piece exactly. The second mark should be a line to tell you the general direction of the cut. When you get the molding to the saw, first check to make sure that the saw is going to be cutting at the right angle, based on the line you drew. Next, line up the saw blade on the right side of the tic plusabout 1/16". If you cut the piece slightly long you have "wiggle room to fit the joint. It is OK if the piece bows away from the wall slightly. Move to the middle of the piece and push the bow to the wall, then nail. Now move to the center of one of the 2 bows you made and nail that to the wall. Keep bisecting the bows and nailing and you will end up with the piece flat to the wall.