"Grip the club with the last 3 fingers of your left hand" (for a righty)...I think we've all seen this mentioned before when discussing the grip in general. But I think it's been somewhat of a secret hidden in plain sight just how important this is and beneficial if truly done right. This clicked a lot more for me when trying out the tips in "Automatic Golf" by Bob Mann.

When you hold the club at an angle like the images provided and then grip the club solely in these last 3 fingers so that the club does not drop or move at all, this allows you to control the low point much better in your swing. It's important that you follow the short thumb and long index finger step as it lets your 3 last fingers angle and lock your wrist. When you hold these fingers with good pressure this does not allow the wrist to extend easily, which would result in the angle of arms and club flattening: a fat shot. Keep this angle between the club and your arms when lowering your arms down to address and throughout the swing. You'll be amazed at how flush you'll hit the ball.