There are so many mental distractions on the golf course, from sand traps to deep patches, that it’s easy to forget about an important part of the game — the connection your hands have with the club. Holding the golf club correctly gives you a feel for the club head, and is the source of everything that follows in a golf swing.
Everyone who plays golf strives for a few basic things in a natural grip. Your swing should be fluid and continuous from the moment you line up the ball to the end of your follow-through, and the club head needs to hit the back of the ball directly to avoid awkward slices. You also want to bring enough power to the ball with a strong swing, but at the same time you need to adjust your grip in order to avoid making the club slip from your hands [waytogogolf.com = source]
The third amateur mistake is losing their leveraged triangle at the top. Many players allow their arms to get behind them at the top of the backswing or allow their right arm to fold or collapse. When you fold your right elbow excessively (greater than 90 degrees), you’ll force your arms behind your back. And once they’re behind your back, it’s nearly impossible to return them to a strong position at impact. You’ll not only lose distance, but also accuracy. Source: 
The second mistake the majority of amateurs make is overusing the legs. While it’s certainly advantageous to use your legs, wildly moving them through the ball will actually slow your clubhead speed and force you to make power-robbing compensations. Remember, the legs serve to support the swing and, as a result, instinctively control the clubface. Source: 
