You must promise something to your audience at the start of your speech, and you must deliver it before the end. That's because speeches are not like conversations. When we have a chat with someone, they get the chance to talk every few minutes. Our audiences, however, have the dubious pleasure of having to listen to us for up to forty minutes at a stretch. In order to make it worth their while, we have to give them something valuable.
We may give them new information, a new insight, or the motivation to change their behaviour. We may give them a combination of things. What is important is that when the applause dies down, they feel as though their time has been well spent. Some speakers prefer not to signal their intentions at the start of a speech. That's fine, as long as your message gets through loud and clear. I prefer to tell my audience what to expect, partly to ensure that they enter a state of eager anticipation.
If you promise to show people "three techniques to improve their business", then don't provide two, or even four (because then they will be confused). If you can bear to do it (and you should, if you are a professional), then contact the organiser afterwards to ask "what did people learn from my speech?" If the answer surprises you, then change your first line. If the answer is "nothing", change your whole speech. And if the answer is what you told them they would learn, ask them how you can help them implement it.