It doesn't matter if you want to hit a 250-yard drive or drain a six-foot putt, when it comes to playing great golf, nothing replaces solid fundamentals. Consider my putting grip. Notice how my hands complement one another and my thumbs point down the handle? I use this standard reverse-overlap grip because it keeps the clubface square through the entire stroke. With my right palm and back of my left hand facing my target, I don't just ensure a square putterface, but a smooth, solid roll, too.
The clubface has the biggest effect on direction, and the position of your hands corresponds to the position of your clubface.
"A square clubface is absolutely vital. to keep it straight, make sure your hands complement one another."