We'll get to the trick shots soon, but for now, there are some practical shots you'll need to be able to recognize in order to play a good game. These are shots that should become part of your basic knowledge bank. They will frequently appear on the table, and the more you play the easier it will be to recognize them. Recognizing them is the first battle and will come with experience. Learning what to do with them is the challenge.
This is a nice way of saying that you're playing the odds. What you're doing in the two-way shot is twofold. Playing a two-way shot involves planning your shot so that the cue ball winds up either in a favorable position for your next shot, if you pocket the ball, or in an unfavorable place for your opponent should you miss the shot. With a two-way shot, you may not have a great chance at pocketing the ball for yourself, so while trying to make the shot, you play a safety at the same time. That way if you miss the shot, you've left the cue ball in such a place that it is useless to, or at the very least difficult for, your opponent.
If you strategize this play, you can't lose with this shot because if your opponent cannot pocket any balls on his or her next play, you'll get control of the table again — this time with the cue ball in a new location where you may have a better opportunity to pocket a ball. Be careful with this strategy, though, because you can just as easily find yourself in a sticky situation without a shot, so be sure that you position the cue ball in a place where you will have another shot, in case you do make the difficult shot.
A cluster is exactly what it says it is: a cluster of balls on the table that look nearly impossible to maneuver — some will be close together while others will be frozen together. You don't want to break balls open unnecessarily, but you may want to try and break up a cluster as soon as you can in the game, because they will only wreak havoc on other shots you're trying to make on the table by blocking shots and causing more clusters.
An experienced player will break up clusters immediately after the break. Take care of this nuisance situation as soon as you see it. If you are a competitive pool player, you'll want to win, and winning means getting rid of problems that will hold back your progress.
The best way to approach a cluster is to get a good look at it and prepare your strategy as far ahead as you can. Don't break up the cluster if there is no playable ball — there has to be the chance to pocket a ball and break up the cluster at the same time in order for the shot to be worth your while. There's no point in breaking up a cluster if you can't pocket any balls unless you can play a strategic safe shot where your opponent has no shot when he or she gets to the table. The worst thing you could do is to turn the table over to your opponent and make his or her next shots all the easier.