Balance is an absolutely key element to every great golf swing. The upper body and shoulders are rotating 90 degrees to the right and left during the swing and with all of this movement in the upper body, it is important that there is a stable base below it to accommodate all of the rotation.
In order to create a stable base, it is therefore crucial for the base to be as wide if not slightly wider than what is above it. Therefore, make sure that you set up before hitting your golf shots with your feet shoulder width apart.
If you are not sure how wide this actually is, just use your golf club to measure it. Hold your club across your shoulders or chest and place the butt end of the club to the edge of one shoulder. Now place your finger and thumb on the shaft at the edge of the other shoulder and this is the width of your shoulders.
Place this measurement in front of your feet and stand so that the butt end of the club and where your finger and thumb measured to are opposite your right and left big toes.
Your stance width is now shoulder width apart and you have created a really solid base to swing from, allowing you to hit with balance throughout your golf swing.