If you have a job that keeps you staring at a computer or sitting down all day then you are a candidate for a tight neck and the swing faults that result
Get your hands on the club properly and learn the correct grip pressure by sliding two tees between your thumb and forefingers and hitting balls without dropping the tees
Tension is by far the biggest killer in the golf swing, gripping too tightly, standing in your set up too long, you need to keep your body in motion and relaxed to properly strike a golf ball