Take off the dual controls; most people's legs can reach the pedals. But on the R22, elbows can still knock the sticky-out bit of the T-bar cyclic, so warn them to be careful. Also warn them not to drop things down the pedal holes - stuck pedals have happened that way. And make them open the door and release the seat belt to prove they can do it; an emergency is not the time to be finding out they can't.
Lastly, if they seem at all nervous, tell them you will be hover-taxiing for a bit, and that helicopters can land anywhere, so you can always let them out if they don't like it. Never had to though; they all love it, but it reassures some people.