Though many people would say the best offense is a good defense, this is not true in baseball as it is impossible for the defense to score. Without good hitting, a baseball team cannot be successful.
Mechanics, at least for young hitters, is one of the most important parts to being a good hitter. Once you advance into higher levels, you must have a quick compact swing or you will be way behind the pitchers throwing 80-90 mph fastballs. There are many many different styles of hitting and just as many variations on technique. However, this will merely be a general overview of proper form.
First, we begin with the feet. While hitting you must have good balance in order to make contact with the ball and have a powerful swing behind it. You should be balanced at all points during your swing. The feet generally are shoulder width apart or wider. This, however, is personal preference. Find a position for your feet that gives you the most balance. Your feet should be parallel to each other and pointing straight at the plate. You should be on the balls of your feet and your weight should be back on your back foot. Your knees should also be bent slightly.
The grip on the bat should be loose. If you are tense you will not be able to swing as quickly. The second knuckles on your hands, the ones you would knock on a door with, should be lined up. You should hold the bat about shoulder height. So, your hands should be shoulder height, in near your chest and just behind your back shoulder.
You should be cocked like this and ready to begin your swing as soon as the pitcher breaks his hands. Stay relaxed and keep a loose grip on the bat until the pitcher breaks his hands then load up and get ready to swing. You are trying to develop a quick, compact swing. This will still have power and will let you hit pitchers of any speed. When you swing you take a step with your front foot and plant it. Your foot will be at about a 45 degree angle. Your hips and your shoulder should move simultaneously. Imagine there is a pole going from the top of your head through your body to the ground. You should be rotating on this pole when you hit the ball. This is how you get the most power. Your hands stay back and only start to drop once your body begins to rotate. Then you should get the bat into the plane of the ball. That way your timing doesn’t have to be perfect.
Most importantly, you should be practicing as often as possible. Whenever you can, get swings in — always focusing on your form and technique, starting slow and then gradually increasing your bat speed.