A good paragraph starts with a core sentence, after which you elaborate. This applies to your first paragraph, the introduction, too. Think of a core sentence that mentions your focus keyphrase, and move on from there. Elaborate and/or discuss what to expect from the rest of the text. You could decide to start with a short anecdote or example, to catch the attention of your reader. If you do so, follow that up with your focus keyphrase as soon as you can, so it’s clear what your page is about. Not just to your reader, but to search engines!