When going to some fancy place, don't overdo your outfit or don't go too casual. Be semi-formal so you can still have some fun accessories or accent to go with your dress or whatever you feel that's right to wear for the occasion. Don't forget to bring a coat!
If you go out, don't go overboard or else people will look at you weirdly. (trust me, i have experience) And don't be too little or unprepared or else you'll regret it in the end. Make sure you have thought of everything that might happen to you when you go out. Remember, money is essential when you go shopping ;)