You might not think your follow through is important.
After all, the ball's already history.
But if your follow through is right, you'll know you have a good swing.
Visualise 'throwing' the club head towards the target and staying on that line for as long as possible.
When you finish, your chest should be facing the target and the entire sole of your right foot should be visible.
If you are overbalancing it is likely to be because you are swinging too fast or too hard - concentrate instead on staying smooth.
Aim to finish with your elbows out in front of you.