As with wedding toasts, winging it isn’t advisable. You don’t need to write a novel—or anything, for that matter—but choose a few basic things to share beforehand. Some ideas: why you love her, why you want to spend the rest of your life with her and how you’ll feel if she accepts the proposal (a cliché like “the happiest man in the world” is fine if you truly mean it). No matter what, don’t forget to ask her to marry you—multiple times if necessary. The shock of the situation may not immediately elicit that “yes” you’re hoping to hear.