There are some fairly straightforward rules about performing at a wedding ceremony. If you've been asked and you're trying to make up your mind whether you'd like to have a role in this wedding, please consider the following:

• Get clear who's choosing the pieces you will perform. Even if they want you to make the choices, it's in your best interest to run it by the wedding couple a month or so before the wedding.
• Make sure it's something you're good at. If you do jazz improvisation on a saxophone, you might not be the best pick for "Here Comes the Bride" (Of course, you might just be the best pick!)
• Make sure you have enough time to prepare. If you do this regularly, you may have songs, or poems or dances that you can pull out of your bag for just such an occasion. But if you're an amateur who needs preparation, make sure you have the time you need.
• Do what you're asked and no more. The worst moments at a wedding are when someone has been asked to read and decides to preach a sermon on what the reading was about. Trust me, if they had wanted you to perform the service, they would have asked you!
• Be completely prepared and in place at least a half an hour before the wedding starts. If you have important questions for the bride or groom, make the rehearsal the day before. It's their wedding day. They want it to be wonderful. They don't care where you sit, as long as it doesn't interrupt anyone's view of them.

If you really feel that you can't get a good handle on any of these, then you really can say no. It won't make the wedding ceremony better if you do it but can't do a good job. Be honest with yourself and the couple. Tell them you're flattered and tell them no if it doesn't work for you. (And tell them early enough that they can get someone else if they need it.) Suggest someone else if you have any ideas.

Oh, and that one last thing. Practice. The day of the wedding is not the right time to figure out you don't know how to pronounce one of the words in the Shakespeare Sonnet that you are just now reading for the first time. It's a joy and an honor to perform at someone's wedding. Act like you understand that! And then enjoy!