Making solid contact at impact is so amazing for golfers. I think that is what the true addiction for a golfer is! But this concept is very hard to us. First, you can always practice chipping or putting. This swing can be easier because it is less moving parts and we are not working on so much power. But as we move to a bigger, fuller swing things can be come erratic. Here is a way to practice and understand how your clubface is coming through contact.
Take a tennis racquet or a badminton racquet (we put an extender on it to make it feel like a full length golf club), practice swinging and concentrate on how the head of the racquet is coming through at contact. At first it might move around like crazy, but with a couple practice swings and concentration you should start to feel those good muscles such as shoulders and hips moving the club face through a lot straighter.