Just GO! Do forms, sparring, breaking, whatever. Don't worry about winning or losing, or looking like an "idiot." You will survive, and everyone else will be too concerned about themselves looking like idiots to be focused on you, so just go, have fun, and learn!
Your instructor should know what tournaments are about, and should be able to prepare you, so trust your instructor. It should be the experience that you go for, not what people think of you. After many tournaments, you will be comfortable with the format, and your skill will increase. Then you can start to formulate a strategy for winning, and train harder based on your previous tournament experience. For now, just go and get the experience!
CM D.J. Eisenhart