Have you ever used a sponge ball (those oversized orange/yellow now sold for kids) and played it back and forth over the net with your hand?
This is perhaps the most basic and most helpful drill of all.
If you don't have a partner, you can do this drill against a wall or your garage door. Once you are proficient with your hand, then do it with a racquet, first holding it short, then normal.
For the backhand, hit barehanded with the left hand first, then with the racquet, with the left hand short on the grip, then with your two-handed grip.
Work on control mostly, doing the three Fs (Find it, Feel it, and Finish), where you give the ball a good lift and at the finish you point to where the ball went with the butt of the racquet.
Brush up and across as well during the contact.
Initially, there will seem to be too little a time to finish the stroke as above, but with practice you'll feel a different rhythm and quite comfortable.
Move like a gazelle or a dancer, naturally, avoiding the skipping steps that complicate your performance.
Adopt a comfortable distance from the net or the wall, where you can easily keep the ball in play, back and forth.
Tennis is like a dance.
Oscar Wegner - TennisTeacher.com