Slowrotor
As a rule ot thumb I teach mystudents in a 300c to hold about 45 knots 16 inchs. This will give approx a 500 ft a minute descent rate.( depending upon wind , temp and weight ). Use a normal sight picture approach, as you get to 150 ft agl where sight picture does not work start gently flaring the helicopter and you will be able to touch down with a zero zero using no more than about 18 inches to cushion on to the ground. Nodanger of vortex ring.