In the Bell 47 (OH-13) my first instructor showed me a backward auto, which is flown precisely like a forward one, but backward. At about 300 feet, he put the nose about 5 degrees nose up, entered from a forward auto, and the airseed bled down to zero, then rearward. Close to the ground, the airspeed was minus 25 or so. He did the flare as a smooth nose down to about 10 degrees, with a stop at a low skid height, and a nice touchdown.