How to Make Solid Contact with a Driver
When your shoulders open too much too early on the downswing, the clubhead will approach the ball from outside the target line.
In other words, you will be cutting across the ball. It's very hard to make solid contact with this type of swing path.
To fix swinging from outside in, swing back to the top and start your downswing. But when you start your downswing, try to make sure your chest is facing right until you hit the ball.
To be exact, you can't really do this. But try to feel like your chest is facing right at impact.
Check Shoulder Alignment
Also, check your shoulder alignment at address because shoulder alignment often determines swing path. If your shoulders are open at address, you tend to swing outside in.
Change Your Ball Position
To hit it solid with a driver, you need to swing from inside the target line on the downswing. However, if you are a slicer, you might want to swing inside out for practice.
To do that, let's experiment with your ball position.
Slicers tend to place the ball too far forward. On the other hand, hookers tend to place the ball too far back.
So let's put your ball in the middle of your stance for practice.
This will feel awkward at first, but it will help you swing from inside for solid contact.
For regular driver shots, place the ball in line with or just inside of your left heel.