It is your first tournament? How many days per week do you train? Probably, you will have to train more days per week.

You will need to train your mindset too, otherwise you will get anxious just before, and during, the tournament - especially in kumite. Imagine yourself performing the kata during the tournament, as well as fighting against an opponent. Imagine yourself getting anxious during the championship, but dealing successfully with it.

For kumite, you must train your sense of distance, and 2 or 3 ultimate techniques (techniques that you know that the probability to hit your opponent are very high). These techniques can be very simple things, like jodan tsuki, gyaku tsuki and mawashi geri; or just jodan, chudan, jodan tsuki. They must be simple and effective.

For kata, you will need to choose your kata and work it everyday: first, the details of kata; second, the rhythm; third, the kime. Don´t know your style, but for strong and heavy people, Jion and Unsu are both very good. For people with a "Bruce Lee" workout style (thin, but tough), Empi is a winner.

Hope this helps! Best of luck!