The best thing a pool player can do to improve their consistency and, thereby, their overall play is to establish a short, repeatable pre-shot routine and do it the same exact way before each and every shot. It can be performed in just a few seconds. Successful players use one for several very good reasons.
A pre-shot routine ensures that you get into your stance the same, correct way every time. Checking the shot angle, getting your cue stick on the target line, placing your feet correctly or anything else should be repeated in the same order before every shot.
A pre-shot routine also lends itself to positive thinking. Besides making you confident that you're doing everything correctly, filling your mind with positive thoughts leaves less room for doubt or negative thoughts to enter your mental picture, and playing pool well requires positive thinking,
Repetition leads to consistency and, just as importantly, dulls the pressure of competition. If you want more consistency in your game, a good pre-shot routine is a great place to start. Take a lesson or clinic and learn how to reverse-engineer your own pre-shot routine.
Give it a try and good luck!