When you have sat out whilst your opponent has made a nice break, you must take more care with your shot preparation, especially if the shot you are faced with is difficult. Sometimes you will start a break with a sequence of difficult shots, in which case you must be patient.
A steady rhythm
Once you are in, aim to build up to a nice pace, not too fast and not too slow. If you play too fast you will become careless and miss the occasionally easy shot or get out of position too easily. If you play to slowly, the game will seem hard to you and you may get distracted by thinking about other things.