Sniff, that's all good instruction and I fully agree. I'd like to add one more point.
As you sight the gun at the target, the gun WILL move, it is impossible to hold it perfectly still, some are steadier than others but ALL move some. The shooter should never anticipate the shot, that is as the gun moves toward the target the shooter should NEVER think "Here it comes, get ready shoot NOW". That is a sure recipe for a low left shot, for a right handed person.
Let the gun move, try to limit it's movement as much as possible, and continue to slowly apply ever increasing pressure on the trigger. You will find your groups centered on the target, perhaps a larger group than you would like to see but centered never the less. Continue to work on your grip, stance, sight alignment and your groups will shrink.
The shot should surprise you.
Slow is smooth and smooth is fast.
If I follow my own advice, sometimes I'm rewarded with a target that looks like this.