You are there to steer the party.
In this gig, you are the Entertainer, not the artist.
Your artistic skill is a given, but it is not why people are at a wedding or a party. People are there to celebrate a wonderful personal event and have fun.
As with most playing situations, preparation is key.
If you are the band leader, there are weeks of work that needs to be done. You will be talking with the bride and/or the wedding planner for maybe as far as a year out from the event to understanding the clients specific needs.
Some have been planning for this day since they were 10 years old and have very speicific ideas, others need more guidance. First and foremost, helping them feel comfortable that you are a proffesional, you know how to keep the crowd entertaned, and how to make her day enjoyable, and something people will be talking about for a long time to come.
Keep in mind what part of the event you are in, and what kind of music is appropriate for that situation.
*Cocktails or dinner -- you are wall paper. light jazz, light rock, even just piano.
*Dance time -- you are the feature. Get them rockin, or start them off slow?
Thats where the planning comes in, but it also is one of those places where your ability to go with the flow is tested.
You may hit with a rocker, and no one is ready to dance yet, pull back to the slower ones. It may be a crowd that needs to warm up, or get drunk.
The reverse is also true, the guests may be ready to rock during dinner. Being aware of the situation, and confering with the bride or the wedding planner as needed can help a great deal in when this occurs.
What do you do when the set list just isn't working the way you planned it?