don't go into it worrying about how you are going to do. just go and do your best. you have plenty of time to worry about being competitive. I think that's why most people go through their lives never accomplishing anything. They are waiting for that magical day when they will be ready. That day will never come thinking that way.
read the rules of the federation. practice the lifts with the appropriate commands. Pick openers that you could easily rep in the gym. Be sure to show up early to get your spot to put your crap. those that have competed know what i'm talking about. take a cooler with you with plenty to eat and drink.
buy your singlet. if possible, have someone go with you to video and keep track of where you fall in your flight as well as remembering to give your next attempt. most newbies forget to give their next attempt. definitely be sure to be there for the rules meeting.
i'm sure there are other things but that's what i can think of off the top of my head.
just go and do it. i have a new member of my lifting team and after lifting with us for one month, i entered him in his first meet. He didn't break any records but he did post a total that he can now work to break the next time around. How many poeple that post on the interwebz can say they even have a total??.. not many.