When you are playing a game where you need to call the shot, you must do so before making the shot.  Such things as kisses or caroms do not need to be told.  If you miss the ball when making a legal shot your turn is over and your opponent will take their turn.  If you are doing a lag to determine who breaks you must both take a solid ball and shoot at the same time, whoever is closest to the cushion will get the break.  You will lose the lag if your ball does not hit the foot cushion, or it pockets, or it jumps from the table, or you cross to your opponent’s side.

Once the break has been determined, the winner of the break will have the first shot.  You must place the cue behind the head string and only hit by the cue.  If the cue ball does not hit the balls directly it will be considered a foul and you will lose your turn.  The opponent can make a choice between taking the break or giving it back to you.

If you have made a legal shot and made in one of your balls that is considered a pocketed ball.  While playing pool you must have at least one foot on the floor when the cue tip touches the cue ball, if not you have committed a foul.

You are not allowed to shoot at a ball while it is moving.  A turn is not done until the balls on the table are still.  What does a foul cost a player?  The turn will end for a player who has committed a foul, the stroke is not counted if the foul is made during the stroke, and balls must be re spotted to original spot.

When making a shot if you do not contact the object ball first it is a foul and you will lose your turn.  A legal shot is when you have hit your object ball first and it can either be pocketed or stop on the table.  Of course if you make the ball you get another turn.

The cue ball goes into a pocket it is a scratch, the turn is lost and the opponent begins his turn.  If you strike a object ball that is not the legal ball you have fouled and again lose your shot.  Hitting a cue ball more than once in a turn is considered a foul, this is a mistake but can happen.  You may also accidentally hit an object ball with the cue tip, this will be a foul and you will again be done with your turn.

If a player accidentally drops chalk on the table or even the bridge this will be considered a foul.  If you jump a ball by accident it will be a foul.  Of course the same is to be said about a ball being jumped off the table, it is an accident but will be counted as a foul too.

These are only a few rules of pool, you can get a more in depth list on the internet or with a book about pool. They might also feature a few billiards tips to help you out.