10 Usability Principles to guide you through the Web Design Maze

1. Motivate
   Design your site to meet specific user needs and goals. Use motivators to draw different user "personae" into specific parts of your site.
   
   
2. User task flow
   Who are your users? What are their tasks and online environment? For a site to be usable, page flow must match workflow.
   
   
3. Architecture – it's 80% of usability
   Build an efficient navigational structure. Remember – if they can't find it in 3 clicks, they're gone.
   
   
4. Affordance means obvious
   Make controls understandable. Avoid confusion between emblems, banners, and buttons.
   
   
5. Replicate
   Why reinvent the wheel? Use ergonomically designed templates for the most common 8-12 pages.
   
   
6. Usability test along the way
   Test early in design using low-fidelity prototypes. Don't wait until the end when it's too late.Know the technology limitations Identify and optimize for target browsers and user hardware. Test HTML, JavaScript, etc. for compatibility.
   
   
7. Know the technology limitations
   Identify and optimize for target browsers and user hardware.Test HTML, JavaScript, etc for compatibility.
   
   
8. Know user tolerances
   Users are impatient. Design for a 2-10 second maximum download. Reuse header graphics so they can load from cache. Avoid excessive scrolling.
   
   
9. Multimedia – be discriminating
   Good animation attracts attention to specific information, then stops. Too much movement distracts, slowing reading and comprehension.
   
   
10. Use a stats package
    Monitor traffic through your site. Which pages pique user interest? Which pages make users leave? Adjust your site accordingly.
    

Good luck.

Source : http://www.humanfactors.com/