All sports have an area of peak performance within the context of a period that many players call being "in the zone!" This 'zone' feels like a twilight state of anticipating, considering, reacting, and executing in the most professional manner, their best moves and plays. But while every player struggles to attain and maintain this state of perfect play and performance, the struggle itself takes away some of the appreciation for all of those times it arrives as magically as it is gone. The state has occurred for me as a runner, a football, softball, basketball, tennis, billiards and chess player. I'm also certain that many players have experienced this state without realizing it or appreciating it ...
Jeanette Lee, "The Black Widow" the professional billiards player, once signed her book for me with the addition of a single word, "Focus!" That idea, along with the competitive cousin, "Concentrate!" are believed to be the cornerstones to achieving an 'in the zone' state of performance. There is a certain prep to every sporting performance that a player goes through in order to attain the best possibilities of a peak performance. Runners stretch and athletes go through a variety of drills. Chess players however don't have an established method of preparing mentally for the oncoming struggle. Torn between the known elements of being certain to get enough sleep, problem solving, analyzing, or just perhaps playing slow or blitz practice games before the big game alternate in priority.
Whichever method you choose it often helps if it is 'your' method - something that within you establishes that comfort zone you will need to play at peak performance, in the zone, effortlessly. The more experience you can acquire, the better your feel for the game and the less volatility in your performances.