A good attacking stroke (like a loop or smash) is a continuous, aggressive motion with a definite weight shift forward. You can’t be tentative, or stop halfway and expect good results. Even where the shot is hit with only moderate pace, the stroke has to flow without interruption.
Get in the habit of “pulling the trigger” by committing to these strokes once you have decided to take them. This doesn’t mean going crazy by swinging with all your might, just recognizing that there will be no turning back or hesitating in the middle of the effort.
Make your decision, go for the shot, and live with the results. If you follow these rules, most of the time those results are going to be just fine.