1) Be on time for the ceremony! (Or even better, be early)
2) Take a VIDEO of the dress bustling and, if possible, have bridesmaids practice this a few times before the wedding. Figuring out the bustle is often the reason for receptions getting significantly delayed.
3) Keep track of the time.
4) Keep track of special items such as the throwing bouquet, garter, cake cutting knife, etc so these items are handy when they're needed during the reception.
5) Please be mindful of where I am set up and who will be sitting in front of my speakers.
6) Your guests will follow your lead! If you're on the dance floor, they will be too.
7) Put together a wedding-day survival kit: first aid, Tide-to-Go stain remover pen, safety pins, etc.
8) You may want to address your guests yourselves during toast time. (Thank them for coming, acknowledge those who have traveled far or who have gone above and beyond to help you make the day what it is).
9) Enjoy the day and don't sweat the small stuff!