Planning your site is very important and will help you stay focused and on track while building out your web site's content. You don't want a haphazard-looking site so a simple bullet point outline will work very well for keeping you on track. For each page that you know you need, simply give it a bullet point. You'll naturally develop layers and ultimately, a hierarchy. You can use the Microsoft Word or Apple Pages templates; a simple idea that will likely save you a fair amount of time.
Save the home page for last, don't get hung up on producing it first as a lot of the content that you're going to generate from your sub-pages will ultimately get used and displayed in your home page.
When you structure your site and all of the web pages in it, avoid using too many layers of directories; you're likely to have more success with the search engines using a more horizontal looking site structure (think "bush" instead of a "tree"). What this means is that you'll have fewer subdirectories but more files in each of them, so keep this in mind while you're planning your site content (try to avoid getting too specialized in your directory/file relationship; if you keep your "categories" slightly more generic then you'll find you can fill each directory with more relevant pages (files)).