If there's any truth to the old saying that "you never get a second chance to make a first impression," then it's especially true in the case of your website's home page.
Your home page is, in many cases, the first online exposure customers will have to your brand. Even your existing customers may redefine how they see you based on their first impression of your site.
This is your chance to establish priorities and express what makes your business or not-for-profit unique. Part of the goal of you home page's content, of course, is also to be as clear and brief as possible.