Be prepared. That's not just the motto of the Boy Scouts or Charlie Sheen when he gives his party guests a tour of the master bathroom; it's the first rule of giving a speech. Write down what you intend to say. Respect your audience.
While we can plan well, there are things beyond our control. It's only a disaster if you think it's a disaster. If you laugh about it and carry on, everyone else will follow your lead and consider your wedding a success.
People speak of friendships lasting a lifetime, acts of courage, moments of hilarity, or what it feels like to watch your son or daughter go through such a momentous rite of passage. Above all, you hear them talk about love.
I'd like to cement my reputation as the Grinch Who Stole Weddings by floating my lil black cloud over to the guests' section, raining on their reception parades with my unsolicited, iron-clad rules for What Not to Say While Giving a Wedding Toast.