as far as over swinging i restrict my hop to no more than a 45 deg turn which n turn adds more resitance and a bigger x factor which gives me much more power than letting m hip turn back further and having a dalyesque swing.

as fas as coming OTT try this website
http://www.newgolfswing.com/newgolfswing07.php
the "magic move" might help
also try to make the first move (with your club) to be vertically strait down for a fwe inches. some people like to l=think of it as dropping into the slot by bringing the right elbow into the ribs. i like to think of it as getting my left arm stuck under my chest where as at the top is was slightly above my shoulder (depending if you have a 1 or 2 plane swing).
HTH