Emphasize the breathing throughout the performance of the kata. Focus on controlled deep breathing during the kata to keep your body well oxygenated while performing the strenuous movements. Utilize the exhale and the kiai at the proper focus points to emphasize the power. Even if you perform a set that has no kiai, a good strong forceful exhale during the execution of the movement at the end of the movement will show the focus and power of the movement. Synchronization of breathing with the movements in karate are absolutely necessary to harness the ki energy that your body and mind generate while performing any movement in karate.
Utilize the Eyes and Head Turns to Emphasize Focus
During the performance of kata the eyes must be focused with a piercing glare. The eyes demonstrate in to a high degree the level of concentration and focus of the karateka. The eyes must be focused in the direction of the attack or defense as if a real person is in front of you as you are executing the movements. The head turn is also important as well. Whenever possible turn the head in the direction of the movement just a split second before the body turns and commits to the next movement. This emphasizes the mental focus and attention of the person performing the kata. Mental focus in this case is directed as if a real opponent is in front of you executing moves that you are focused in on during the kata. This head turning is one of the markers that a judge looks for when a kata is performed. Lack of turning the head at the proper moment shows a reduced degree of focus and attention.
Balance and Form
Good kata always demonstrates a high degree of balance and an adherence to the basic proper form of karate. Balance is achieved through continuous practice and by trying to maintain upper body weight directed directly over the hips at all times when in the upright position. This is done by maintaining an upright posture with the shoulders directly over the hips as much as possible. The spine from the hips all the way to the base of the skull including the neck is kept as straight as possible. Movement and momentum are controlled at all times to maintain the "center" and keep balance. Over commitment to a movement will result in imbalance, under commitment results in a reduction of kime or focus. Counter movement also helps to a great degree in maintaining balance. Counter rotation of the body in a movement such a roundhouse kick keeps the body balanced. Putting as much power and emphasis in the retracting or "passive" hand during the punch also accomplishes the same counter movement which helps the karateka maintain balance during the execution of the movement.
Form is maintained by placing much attention to the little details of the basic movements. Practicing the kihon is the way to improve the basic movements. This practice of the basics is never ending with improvements constantly being built through repetition. The practice of kihon never ends, thus the karateka's form continually improves throughout the years. One needs only see a master perform a simple punch to see the difference and the effect of continual practice of kihon. Through improvement of the kihon the pieces of the kata are improved thus resulting in a better kata overall.
Saving the Best for Last
When performing a kata in competition, usually there will be an elimination round and then a final round. Many tournaments require you to do a different kata in the final round than in the elimination round. So long as you are confident that you will make the finals, you should always save your strongest kata for the finals. The other competitors are doing the same thing as well so you need to try to make yourself stand out from your competition by doing your best in the final round. Resort to doing your best kata in the eliminations only if you feel you will not make the finals should you not do your best kata during the preliminary round.
Make it Flow
The movements of the kata should flow much in the way water rushes down a stream. Fast at times like water through the rapids and slow at times like water moving through a slow section of a stream. The key in the flow is making the transitions of the sets become one with one another. The first set flows into the next set yet the movement is deliberate to demonstrate the separation of the movements from one set to another. The rhythm may be broken in sets of slow and fast movements, but like the water in the stream it continues to flow continuously without breaks in the flow. Even when a pause is taken to show the focus of the movement, the energy and flow of the kata continues.
The kiai is the shout used in karate that is used to unify the power of the body and the mind into one focused moment. It is utilized at the time of either an attack or defense when contact is made with the opponent and maximum power is called upon. The word "kiai" literally means to match "ki". Ki is the internal life force utilized to generate power in karate. The matching of the ki is the matching of the physical ki with that of the mental ki. The shout is short and strong should come from the abdomen, not the throat. The actual word uttered varies. Some shout the pronunciation of the letter "I", some the letter "E", some "Yaah". What is said is not so important, how it is delivered is. Delivery should be forceful and loud. The kiai is not used to scare the opponent as many think but is used to unify body and mind as one to generate power.