I put grippers (TrueGrips) on the corners of my rulers and I have also used sandpaper. I also use a woodworkers clamp to hold my ruler but that is due to a bad left shoulder which hurts too much to apply pressure to the ruler. I had forgotten about placing the end of the ruler against the wall, but I used to do that and it helped also. I know someone on here can tell you the name of the product that is applied to the back of the ruler because I've seen it mentioned several times. I'm sure it's available from JoAnn's.