Just go out and enjoy. If it's your first ever, I presume you are playing for your handicap, so all the more reason to go out and enjoy yourself as it gets a bit more serious once you get one. If you already have a handicap and this is your first competition you can win, then the best advice I can give you is don't make the same mistakes time and again. If it goes out of bounds make sure the next doesn't, if it goes in a bunker make sure it comes out first time, if it goes into trouble make sure it comes out (even if it means a penalty drop).
You can see where I was going, just don't waste shots.
Enjoy it. If you are unsure about how to proceed with any rulings take your time and ask. If you get into trouble play out the shortest way and use your shots wisely. If you look at every hole as a par 5 and shoot 90 you'll have a nett 66 and will be lauding us with triumphant winning posts. That sickening feeling you'll have on the first is normal Get use to it and enjoy the feeling. Go out and have fun as thats what its about at the end of the day whether you play well or not