How to Hit a Baseball

Steps
Stay calm and take deep breaths and it will come out. You won't be able to hit if you're nervous.
Stand parallel to the plate in a loose comfortable position with your legs about shoulder width apart and knees and hips well bent and your body weight perfectly centered in the middle. Your hands should be about five inches away from your body and only a couple inches above your shoulder height.

Batter Up!
Imagine a box shaped area for following the ball. When the pitcher goes through his or her motion, imagine a box around his or her shoulder where the ball comes out. This will make it easier to figure out what he or she is going to pitch.
Wait back as the pitcher is in his windup with about 60% of your body weight on your back leg. When the pitcher breaks his hands (separates his hands which were previously in his glove)you should take a light smooth stride only about 2 inches long.
Prepare for receiving the ball. As your front foot steps forward your body weight should be shifting back to about 80% on your back foot. Your hands should be moving backwards very slightly while keeping a 90 degree bend in your front elbow. With the backwards motion of your hands, your front shoulder should be going forward towards the plate. All of this is done in very quickly and is known as the load.
Keep your eyes on the ball. Once the pitch is in the air you have a fraction of a second to identify what pitch it is and where the location is, then you pivot, twist your hips and bring your hands straight down with the knob of the bat (small round piece at the bottom of the bat where you place your hands) going straight to the ball with your body weight being transferred back to the center. You then extend the bat while keeping it on a level downward plane, once you make contact you flick your wrist and extend the bat pointing the end of it to the pitcher and simply finish with the bat on your shoulder.

Tips

Keep your eyes on the Baseball!Throw the knob at the ball but don't hit the ball, with it extending out. The barrel should hit the ball in the middle and it will go far.
On inside pitches, you should hit the ball out in front of your body, on an outside pitch you should let the ball get back in the zone and hit it behind yourself or at your body, on a pitch down the middle you should hit it right on top of your body with good extension.
When you identify a curve ball, sometimes it looks like it's going to hit you. Don't buckle backwards, just stand your ground and if anything, turn into it and stay low, which will let you hit it with much more consistency and power.
Don't be afraid of fast pitchers - the faster the pitch, the further the ball will go. If you see the ball coming at your midsection, don't lift your hands and let it hit you in the ribs, press your arm into your side and let the ball hit you in the arm (it's much better than taking one in the ribs).
Keep a loose grip so that you are relaxed, however, don't hold on too loosely or you will lose control of the bat.
When attempting to hit a curve ball, hit it right after it breaks. Swinging before it breaks will get you fooled.
Some people in baseball wreck their baseball career by always trying to hit homers. Sharply hit line drives which get you on base are much more effective and common than home runs. A fly ball hit to an outfielder is almost a guaranteed out.
If you have a reputation for hitting the ball to the outfield, sometimes its effective to bunt. This confuses the other team and can cause you to get on base without getting a sacrifice.

Warnings
Keep your back elbow up!
If your top hand (right hand for a right-handed batter) is not palm-up when contacting the ball, you will hit a ground ball.
Always wear protective gear and especially a helmet, you never know when a pitcher will slip up (accidentally or on purpose).