The title of your web page is extremely important. Not only are the words in your title indexed by the search engines, but they tend to put a very high weight on your title words when determining relevancy of your web page to a search query. Also, when available, the title appears as the link name in the search engines and as such can aid in guiding users into your site. Additionally, the title appears as the title of the browser window when a user is at your site, and if you are lucky enough to have a user bookmark your site, the title will appear as the name for the bookmark.
The heading and initial paragraph also bear more weight as search keywords in the relevancy formula for most search engines than the remainder of your body text. The assumption by most search engines is that you will summarize your page in the opening paragraphs. This is a tried and true tradition in newspaper and magazine articles, and should be practiced on your web page too. Not only is it important in your search engine ratings, but the search engines that don't honor the description meta tag will usually use the first few sentences of your site as a site description (Mann).
It is important that your web page introduce your site in those first few sentences. Before applying this technique to my own web pages, MetaCrawler, one of the sites that doesn't use the description meta tag, showed my site description as a javascript I was using. This was a totally inadequate and inaccurate description. A minor modification to my page allowed MetaCrawler to present an accurate page description. If your site is mostly graphics, it is especially important to provide alternative text for all your image tags. Not only is this helpful to users who prefer to surf with graphics turned off, or who have text only browsers, but many of the search engines will index the alternative text (Mecklermedia, Content).
The last item to help your relevancy in the search engines is the page content itself. Use heading, H1, H2, etc. tags appropriately. These words figure high in many of the search engines. The engines index all the text on your page. Make sure you keep your page focused on the audience you are targeting and avoid irrelevant chatter.