Here is a summary of usability essentials for web pages:

1. Don't make the user have to think
This is the number one usability rule as expressed by users. Web pages should be self-evident, obvious, and self-explanatory. Buttons should have short text and look clickable. It's a good idea to show some reaction to confirm that a button is a button. Most visitors to a web site won't move the mouse pointer over menu items to expose fly-out or pull-down menus.
2. Design for scanning not reading
Users glance, scan some text, and click on the first reasonable option. People scan Web pages, they don't read them. Here are some things you can do to make sure users understand as much of your site as possible:
a. Create a clear visual hierarchy to show relative importance of content
b. Take advantage of conventions
c. Break pages up into clearly defined areas
d. Make it obvious what's clickable
e. Minimize clutter
3. Users like easy, direct choices
Make each click an unambiguous, obvious, and easy choice.
4. Omit needless words
Get rid of half of the words on each page, then get rid of half of what's
left. This is especially important on home pages and portals.
5. Navigation: Use street signs and breadcrumbs
The back button accounts for 35 to 40 percent of all Web clicks. Navigation must appear on every page of the site and should include at least the following three elements:
a. Site ID
b. A way home
c. Hierarchical and Section identification
Your navigation should answer these questions:
a. What site is this?
b. What page am I on?
c. What are the major sections of this site?
d. What are my options at this level?
6. Your home page should convey the big picture
What is the site about? Use a good short tag line and welcome blurb. Rotate site promotions. Remove everything nonessential.
7. Most Web design usability arguments are waste of time
All Web users are unique. There are no average users. There are no simple "right" answers for most Web design questions. What works is good integrated design that fills a need, that's carefully thought out, well executed, and tested. The antidote for the usability debate is to ask specific questions and test with real users.
8. Search is the crutch of ineffective design
If your site requires search, there is likely a serious problem of organization and navigation, and there may be other serious problems. Most searches fail and the user will immediately leave the site for greener pastures. Unless you have Google's funding, leave searching to the experts and work on the real problems!

Web application usability is an entirely different matter! Call Reed for a more complete overview.

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