State your purpose directly. The less specific you are, the more likely you'll lose your audience's attention. Give your audience a firm grasp of the content you'll cover in five sentences or less.
Impart a piece of news that your audience may not have heard yet, and keep it audience-specific. If your intended audience is stay-at-home moms, don't open with the price of gold. You could, however, mention recently legislation that will affect the mother's child. Do not mention any news widely talked about. The opening will sound unoriginal.
Connect a story with your audience. The story must entertain the audience and tell them what they'll gain from your overall content. Tell a story about someone who needed help, used your advice or approach and was better because of it.
Describe a fact that your audience will find interesting. For example, if your audience is a group of plumbers, you might dig up some lesser known fact about the history of plumbing. Always relate the fact directly to the rest of your content.