Position your elbow correctly
I had always had trouble in the past coming over the top and hitting either a fade or slice but I started practicing holding my right elbow to my side and closed my stance a little by dropping my right foot back and now I draw the ball and hit it much further. That being said where is the perfect position to have my left elbow throughout the swing so that I can practice before our season starts.
A: Stand without a golf club holding your arms in front of you, left palm down, right palm up. Make a half turn to the right, let your arms come with you. Your right elbow should hug your ribcage with a slight fold, and your left arm follows remaining long. Rotate to the left letting your arms follow your body and rotate your forearms. Now your right arm should be longer than your left, your right palm down, your left palm up. You can see that your left arm is now folded with your left palm and left forearm pointed upward. As you can see, your left arm lengthens in the backswing while your right arm folds with the forward swing being a mirror image. To answer your question, the left arm gets wide going back and then folds and rotates coming through.
Drop me a note if confused.