Even if proposing a toast is the only public speaking that you will ever do, there’s still a right and a wrong way to do it, and there is no reason why your performance should be anything but successful.
As with having to make an impromptu talk or deliver a eulogy, in almost every toasting situation the three criteria for a successful speech are present, otherwise you wouldn’t have been asked to do it. You will have earned the right to propose the toast by virtue of your association with the person being toasted. You will have some emotional investment in the event through your presence at it, which, combined with your respect and fondness for the person being honoured, means you will meet the criterion of feeling strongly about it. Finally, if there’s any doubt about the third criterion (wanting to do it), just remind yourself of what an honour it is to be asked.
On the other hand, if none of the three criteria applies, for example if you don’t really know the person and have no strong feelings about the event, you should decline the request, even if you’re an accomplished speaker. Everyone, and particularly the guest of honour, will know that you’re just playing a role, and your participation will in no way enhance the event or your reputation; in fact, it’s apt to diminish both.
Whether you intend to speak “off the cuff,” just use some notes, or speak from a marked-up script, as in every other speaking situation it is extremely useful to initially write out your toast in full. Writing it out in full allows you to edit, organize and time your material as well as to rehearse it. Even a short toast should be rehearsed, if for no other reason than to identify and avoid cumbersome phrasing or words that you would have difficulty pronouncing.
Any toast should be kept short and to the point. Furthermore, everything you say should be both relevant and interesting. Keeping a toast short, relevant and interesting will allow you to avoid the most common trap that people fall into when proposing a toast, which is making speeches about themselves. The audience wants to hear about the person being toasted, not about you, although it’s always appropriate to include information establishing the relationship between you and the person being toasted, provided it’s both relevant and interesting. For example, when toasting a bride it might be relevant that you met her through playing bridge with her parents, but it’s not too interesting; remarks about her university geography thesis might be interesting, but completely irrelevant unless that’s how she met either you or the groom.
Never, ever, tell a joke when proposing a toast. I cannot think of a single toasting situation in which telling a joke would be appropriate. However, it is fine to include an amusing anecdote involving the person being toasted, particularly if it’s combined with establishing your personal relationship.
The length of your toast will depend entirely on the nature of the event and your relationship with the person being toasted. If your toast is only one of many throughout an evening or luncheon during which a number of people are being honoured, you should keep it very short – not more that a minute or two. On the other hand, when toasting a bride or groom, it’s perfectly acceptable to speak for up to five minutes or more, provided always that your remarks are both relevant and interesting.
Finally, and very importantly, don’t look at the person you’re toasting until the very end of your toast. Instead, make eye contact with all parts of the audience until you ask them to join you in the toast. Then raise your glass, turn to the person being toasted, and conclude your remarks, emphatically and clearly, with the actual “To the Bride!” or “To Herb!”