Once your page starts to show in a visitor's browser, you have about 5 seconds to get their attention. Good headlines give people a reason to keep reading. They help get attention, and they break up the text into logical pieces. Titles are what a visitor sees in some of the search engines, and they're what gets shown if he bookmarks your site. Tell them what you're offering right up front and watch your sales go up.
Untargeted advertising is the fastest way known to blow a budget and get no results.
Know exactly who your audience is, and market directly to them. Ignore everyone else. It's hard to believe, but there are a lot of companies who don't track their responses, and who don't test various approaches against one another. This is so easy to do online. Don't neglect it.