When the big day comes, be ready
The big day can tower over you.
Have a detailed schedule
In case you haven't caught on to the theme throughout this Web site, to be successful at event planning, you have to plan ahead. The same goes for the actual day of the event.
Prior to the big day, have a detailed schedule and resources ready for every aspect of the event: set up schedule, sound check time, emcee outline, set times, clean up schedule--anything and everything. E-mail this schedule to your members the night before so everyone is clear and have a few copies at the event, too.
Have one main point person
When there are too many cooks in the kitchen, chaos ensues. Assign one person to be the event captain. All questions and issues should be fielded through this person, and the captain should be the person vested with the responsibility of delegating tasks.
Have a back up plan
It's inevitable that things will go wrong the day of your event, so be prepared. For example, if you're having an outdoor event, make sure you've booked a rain location you can easily switch to the day of.
Some things you can't prepare for, so make sure you know who to go to if things go wrong. If the event services office is closed at the time of your event, for example, but no one showed up to run your event's AV, what do you do? Find a night manager at the info desk, and he'll get AV services to come to your event.