Fighters get excited and nervous and hold their breath. It is important to maintain breathing and breath control to remain relaxed and in control of the match. One excellent way to do this is to kiai frequently and loudly. It forces you to take deep breaths, demonstrates a fighting spirit, and may demoralize an opponent.
Just as in other sports, such as golf and baseball, you must continue with the motion after contact (point) is made. Do not stop attacking after you score a point. You may think you scored an obvious point, but the judges may not have seen it, so keep attacking until told to stop. Likewise, when you are scored upon, do not stop your action; instead, quickly respond with counterattacks. The judges may not have had a clear view of the technique, but if you react as if it was a point, they may call it a point for the opponent.
Many fighters new to tournament competition focus on abdomen targets too much. First, because it is a low, many times exposed target, and then, since they are unsure of their control, they do not want to excessively strike the head. Also, many junior belts who try to go to the head too early in competition are too restrained for fear of hitting their opponent. The abdomen is always a good target, but do not get caught up in the competition and let it become your primary target in all situations. Learn to attack all legal targets.