Weeks before tournament
Do your recon. Know the location, the expected weather conditions, the environment of the location (lighting, heating, air conditioning, etc.), the expected skill levels of the competitors, the number of competitors, the rules, etc. Train according to your reconnaissance.
Day before Tournament
Do not train. Relax and do relaxing things. Do not change your eating habits except to eat plenty of complex carbohydrates for the evening meal. Get plenty of sleep. If you must rise early to commute to the tournament, then go to bed earlier. If the tournament will involve a long commute, consider arriving the day before. Do not make any drastic changes to your daily routine. Do not drink alcohol the night before. On tournament day you want to be relaxed, alert, healthy, and prepared.
Arise in plenty of time to take care of morning chores and prepare for departure. Estimate your commute time and add extra time for potential problems, such as heavy traffic. Time your morning meal so digestion will not sap your energy at fighting time. Arrive with plenty of time to take care of tournament business, such as registration, meetings, or weigh-in, and to allow yourself to acclimatize to the environment, such as temperature, humidity and noise level. Familiarize yourself with the arena. Know where your assigned ring is located and be near it as your fighting time approaches. Know where the near restrooms are located and where tournament officials are located. Depending on when you ate your morning meal and when your fighting time is, you may need to eat more to keep your energy level up. Eat light high-energy snacks not hot dogs or pizza. Time your warm-up so you will have a light sweat when your fighting time arrives. Stay hydrated. The tension and excitement of completion will cause more hydration than usual. Drink a lot of water, but do not over do it.