The majority of club golfers swing across the ball causing the ball to slice. This is caused by swinging their shoulders and club at the ball when they start their downswing and not enough leg and hip drive into the ball.
Two key positions you want to see at impact is 1/ position your left hip in front of your left foot and 2/ make sure you have rolled onto the inside of your right foot with your heel off the ground.
If you can start the down swing by bumping your hip and driving your legs to the target you will ensure that you hit the ball from the inside and follow through down the target line every time.
Great golfing!