Any pro will tell you that having the correct golf grip will make or break your game. Harvey Penick put it best when he wrote, "If you don't have a good grip you don't want a good swing." Ben Hogan also said that "golf begins with a good grip." Even your local driving range pro will tell you that a good grip is the fundamental foundation for a good golf swing.
The reason why the correct golf grip is a must is clear when you think about it - your hands are responsible for holding on to the clubshaft so that your clubface is square on impact. While your swing may not be in the 100+ mph category of the pros, even a slow swing speed creates high enough velocity that you can't make hand adjustments to correct any clubface alignment issues as you close in on impact. That's why every player needs a good golf grip as a fundamental element of the swing.
In an ideal world, you'll have a golf grip with a neutral hand position. Neutral hand position should result in your hands and clubface consistently facing the target when you make impact. A good golf grip should feel natural - the same way it is when your hands are relaxed and hanging by your body palms inward is the same way you'll go about setting up your grip. You'll tilt your right shoulder down to position your right hand slightly lower than the left. That's proper golf grip positioning for right handers. Southpaws should have the left hand lower.
When your golf grip is finalized, your palms should be facing each other, with the back of your left and and palm of your right hand aligned with the target.
While it's difficult to learn the correct golf grip just from reading about it, training aides such as the Refiner Swing Trainer product line train you to have the proper grip while also working to refine your swing.