As to preparing for a tournament, train the same as usual, just harder and more of it. Spar as much as possible using tournament rules so you will not make any mistakes at the tournament. Try to spar people with whom you do not normally spar. Try visiting and sparring at other schools within your association so you will get to know how your possible opponents fight.
For pattern competition, practice performing the pattern exactly as you want to perform it in the tournament. In competition, you will perform as you have practiced. While training, if you just go through the motions of the pattern, then, without extreme concentration, this is the way you will perform the pattern at the tournament. When you finish performing a pattern properly, you should be winded. You are acting out a fighting sequence so you should be performing the pattern as if you were fighting for your life and putting everything into it.
When preparing for a big test at school, if you have studied long and hard and know the material, then all the questions will seem easy. The same is true for a tournament, if you train hard and prepare for it, it will be easy. You may not win, but it will only be because the opponent was better at that moment, not because you were not doing your best.