The best way to avoid accidents in an R22 (other than not flying it at all) is to stay in current flying practice on it. The R22 is not an easy helicopter to fly and can bite unforgivingly if mishandled.
Unfortunately, once PPLH qualified, few pilots keep the tempo of flying that they had during their training period. Skills perish, ego assumes that a PPL is a badge of excellence and rusty pilots take to the air in a machine they are not fully in control of; there is no experience to rely on and so anticipating problems is difficult.
Now we are left with a low time pilot reacting to the aircraft, often way too late and sometimes with inappropriate control inputs - is it any wonder there are a lot of R22 accidents?
Oh, and it's killed a whole lot of very experienced R22 pilots as well...