Put on a cute graphic tee. Ones with sayings on them are great. Put on a hoodie if it is cold.
Wear some cute jeans or shorts.
For makeup, keep it natural. The last thing you want is for someone to mistake you for a clown.
Base your hair on what you plan to do. If you are going to be riding very fast rides, then leave your hair down with nothing in it. For people who aren't going to ride fast rides, then put your hair in a ponytail.
Wear flats or sneakers. You are going to do a lots of walking. If you are riding fast rides then wear sneakers.
For accessories, keep it simple. You want to enjoy your night and not worry about keeping up with jewelry. Wear a bracelet or necklace that is cheap and you would not freak out if you lost it.
Put on a favorite shirt. Wear a hoodie or sweatshirt if needed.
Make sure it isn't full of holes or has a bunch of stains on it.
Pick out your pants. Don't throw on whatever you can find.Take time to decide what goes with your shirt.