Learn from an experienced officiant if you can. For the first ceremony I officiated, I got a permit from the city to perform the ceremony for friends of mine. But once I realized this was my path, I went through an ordination program. Even if you're a friend of the family, I think it's a good idea to do a good bit of research —and speak to a professional officiant—so you can write a ceremony that addresses the desires of the couple, and prepares for the unknown.