How good is your posture at address?
A golfer's posture at address will ultimately determine the quality of their body motion and balance and how it allows them to maintain these angles throughout the golf swing. What we are trying to achieve is an 'athletic' position to start the golf swing.
Too many golfers tilt their spines too much over the ball with straight legs or over flex their knees, with their head stuck in their chest and too upright a spine angle. The result will require the golf swing to make compensations throughout to deal with these basic errors in setup.
Build from the ground up! The best players in the world get out of position at address, which then will cause their game to go off. They will always look to make sure their basic fundamentals are correct first.
Look at the picture of world number 7, Rory McIlroy. We may not all be able to hit the ball the distances he can, but we can definitely achieve and improve our body position at address which will ultimately improve our technique.
To achieve this, stand upright with your feet shoulder width apart (distance between your heels is shoulder width) and your feet turned out slightly 5-10 degrees. Hold the golf club at arms length and down so the club is parallel to the ground. Now maintaining a straight spine tilt from the waist/hips until the club reaches the ground (don't bend from the chest or stomach).
Now simply flex your knees to achieve balance. Your weight should be on the balls of your feet, not toes or heels. What you should see is your spine angle is tilted but straighter. Weight is on the balls of your feet and your arms hanging down. If you were to draw a line through your shoulders it should pass down just over your toes. This is worth practising in front of a mirror a few times so you can check it's correct.
Ok now your angles and posture are correct take time to get used to the changes but also check your set up against a professional who is of similar height and build.