Bad rolls, spit outs, uncanny tree hits, and slipping on the teepad will all happen in a tournament setting. Go in and prepare for the worst and be ready to shrug it off and move on.
Also, in lower level AM divisons par golf usually scores well. Don't take unnecessary chances to get one birdie, don't try and make up a 5 on the next hole, and don't let your competition change your game, even if you get your butt smoked.
Now that I may have worried you enjoy it! Tournaments are a blast. When you stop having fun, remind yourself that you are out there to have fun.
Lastly, I would advise playing Rec, intermediate players usually have a better feel for a tournament pace and adhere more closely to tournament courtesy rules. Also, it would be much better psychologically to place better in Rec even if you stomp the competition. You can always compare your scores to the other divisions afterwards. Best of luck!