Your shots aren’t going where you want them to, largely because you’re not returning the face to square at impact. A tennis racquet can help. How? Its large head makes it easy to see how the “face” is angled at all times—what we in the business call "critical feedback." With the racquet in your left hand only, channel your inner Nadal and make a backhand return.
Rotate in a mini-backswing (photos below), then swing the racquet through as you rotate forward. At impact, the face of the racquet should point at the target, with your hips open 45 degrees and your shoulders open about 20 degrees. Finish at waist height, then add your right hand to the grip. If your right hand can’t reach, you’ve failed to rotate enough. With a few practice swings, you’ll groove the feel—and a bona fide smash.