On the subject of R22 RPM in autos, the key is to keep the 60 kt attitude. The R22 RPM is very sensitive to attitude changes, keep your eyes OUTSIDE, do not stare at the airspeed dial. Set the attitude and hold it, then control the RPM with the lever. Start the flare when the RPM is at the bottom of the green arc, as you know it will rise in the flare.
If I was given that advice when I was learning I would have accepted it because I didn't know any better at the time.
Now I know better and I only need to keep a minimum of 60kts attitude when approaching the ground, if higher than 500 feet it is not necessary. (you should be varying the airspeed to either stretch or shorten your aiming point). Also during the flare I would raise the lever a little to contain the rpm, no need to let it rise.