This will give you a basic layout of how to strike a soccer ball so that it has power and accuracy.

Step 1: Before Striking the Ball.

Obviously, make sure you have proper shoes on (preferably soccer cleats) and be sure you're kicking the ball at something like a wall or a goal so you dont have to run and get it everytime.

Place your ball where you want to strike it from. Stand behind the ball so that you are facing the target that you are aiming at. Now, take about 3 steps straight backwards. If you are right foot dominated, take one step to the left. If you are left foot dominated, take a step to the right.

Step 2: Before Striking the Ball

Now for the most important part. Once you are lined up behind the ball, take quick strides that are about the same size as the ones you took when walking backwards.

On your last stride, you want you non kicking foot to be "planted" right next to the ball. As soon as your non kicking foot hits the ground, your kicking leg should bend at the knee so that you heel almost touches your behind. Lock your ankle so that your foot is flat and forms a straight line with your shin.

I was searching google images and i found this awesome picture that explains everything I said in a few sentences :D.

Step 3: Striking the Ball.

Before doing this step, i would practice doing the 2nd step 5-6 times just so it comes out smoothly and you dont hurt yourself.

Carrying over from the 2nd step.... once you have your leg back, you will (obviously) want to swing it through and kick the ball. As you are about to kick it, do NOT lean backwards. This is a common mistake that all people make. Leaning back will cause the ball to go high into the air, and probably over your target. With that in mind, try to swing your leg "through" the ball which means let your leg keep going forward even after you kick the ball. Be sure to keep your ankle locked. Aim to hit the center of the ball. After your foot makes contact with the ball, your momentum should bring your foot through the ball so that you land on your kicking foot.

This will take ALOT of practice, so don't expect to get it right in the first 20 tries. Good luck and if I need to clarify please don't hesitate to ask.