Making a web site is like starting a garden. If you just dump seeds in the first available spot, your harvest will be poor. You must start by planning.
You can divide your web planning into three steps, making sure that your web site is sensible, usable, and accessible.
You need content that makes sense to your audience. That means having a clear idea of who your audience is. Once you know that, you can figure out what the message should be. If you can't clearly state what the audience and message are, the chances that your site will work are poor.
Having great content is not a guarantee that it will reach its audience. It must be available and usable. Your visitors should be able to find it quickly, and to interact with it in a way that is simple and not frustrating. This is easier said than done; when your content is complex (there is a lot of it or there is a sophisticated hierarchy in it), it can take changing a site's interface several times before it is usable. Observing users interact with the site and noticing their failures is the best way to make improvements.
Finally, once you have your stuff organized into a usable structure, you need to make sure it is usable for everyone, including users with visual, auditory, and motor disabilities. At this point it might become clear that you need to sacrifice some of the presentation tricks to make the site accessible. This is particularly likely if you have never dealt with web accessibility before; in that case, it would help to get a basic familiarity with it early on, before starting your project.
Most of us believe we don't need coaching to create sensible content; communication is what we do daily and we generally have a high regard for our own skills in that field. Picking up and browsing a basic text book from an introductory communication course or a public speaking course will help you have a clearer idea of how to craft good messages for your audience.
Usability is a new field for most of us; a good starting point to learn more about it is Nielsen's list of usability principles. Accessibility is often a difficult field even for web professionals - WebAIM's introduction to web accessibility is one of the most authoritative short treatments of the subject.
Please supplement your self-guided learning with a free web consultation from OIT - we can save you time by pointing you to the right resources and helping you avoid common mistakes early on, when they are still easy to correct.