If you have the dreaded flinch (anticipation) buy some snap caps. They are dummy rounds with internal springs so when you dry fire the revolver it will not damage firing pins etc. Have someone load the snap caps along with live rounds. This exercise supposedly helps.
When rounds go low and left it is usually because the firer squeezes/jerks their hand just before the gun discharges. If the backstrap doesn't fill your hand, the grip will be pulled in and down by the contraction of the lower part of the hand. I had this problem when I first started shooting my Officier's .45 (it has a straight backstrap where all my others have a curved backstrap). The solution is to 'pull' straight through the trigger movement (or change grips..). Another solution is to modify your grip (as in hold). I use a heavily modified weaver type of stance. By readjusting the left hand (for a right handed shooter) I can counter the long, heavy trigger pull of my revolver... (btw it still works under pressure as it is all macro movements. Pulling straight through takes to much concentration for me).
hope this helps, if not it is still fun to practice.