I host weddings on my sim regularly...here are some of the things I tell the happy couple:
1) Make a backup plan in case SL goes into the toilet on your wedding day.
2) DJ - unless you are buying a package deal someplace, you'll want someone to handle the music. They will need their own stream. It is a good idea to test the stream about 1 hour prior to the wedding to make sure all is working. Plan for them to have "house" music going starting at about 20 minutes prior to the ceremony.
3) Officiant - this is the person performing the ceremony. Make sure you go over all details and plans with them before the wedding day. Even write a basic script and timeline....
4) Items - unless you are buying a package, you'll need some basic items. Will the officiant stand at a podium? What sort of poses will the couple need? Will you want poses for the maids of honor, etc? You'll want to rez those items and finalize placement at about 1 hour before the ceremony.
5) Rehearsal - best to get everyone to do a quick walk-through just after the items are in place. This is a good time to figure out who is going to say "go" for the start of the ceremony and who is going to cue the DJ and bride. Assume that the bride will be out of chat range and everything needs to be handled via IM.
6) Location arrangement - you can stage a wedding just about anyplace, be creative! The one thing to keep in mind is that they whole thing needs to take place within a 20m space so guests and everyone else can stay in chat range.
7) Guests - you'll be limited by the SL as to how many. They will begin arriving about 20 minutes before the ceremony and at least half of them will be late. Plan for a 15 minute delay in your start time to accommodate latecomers. Someone in the wedding party - NOT the bride or groom - should have a copy of the guest list. This is SL and people wander haphazardly around. The landowner will be able to boot anyone who makes trouble but it takes time to find out whether or not they are an invited guest behaving badly or an interloper.
Organize, organize, organize. Do as much planning as you can (while still keeping in mind that this is SL, sometimes sh*t just happens and you have to roll with it.) The better you plan before hand, the more time you have on the happy day to worry about hair, dress and why the hell you can't find your shoes in inventory.
