Appearance 

Appearance refers to the styling of hypertext documents. This includes fonts, layout, colors and images. This is best accomplished with the use of a stylesheet (CSS or cascading stylesheet document) because this separates appearance from content and makes it easier to make changes across a whole site. The style or appearance of a site should appeal to the site's target market and apply the principles of graphic design effectively to assist the communication process.

Organization

A web designer must consider not only the appearance of the site, but also the organization and structure of the content, or information architecture. This should be logical to assist the user in finding the information they are after.

Navigation

The navigation system of the site should clearly show the information hierarchy of the site and allow the user to move vertically or laterally in the hierarchy while being able to see where they are and get to any other section of the site quickly. Navigation that is badly designed can lead to frustration for visitors. 

Content

Content is essential!  - the more the better. I encourage my clients to write as much as possible relevant content to put on their site. It is true that people do not always like to read much on screen, but the search engines only see text and they will index your site based on the text on it. If your site's text content is lacking in relevance or simply lacking, it will not appear in search results and hardly anyone will find your site in the first place, no matter how cool it looks!

Usability and Accessibility

The site must be usable by the people it is aimed at - and ideally by everyone, including the visually impaired who browse the web with reading software. This means that HTML content should be available in addition to Flash, and HTML code should be clean and simple. This is achieved by applying styles and graphics using a stylesheet, and writing valid HTML.

Interactivity

We instinctively pay attention to things that change and move. We also enjoy the control of causing events to occur by our own actions. For these reasons interactivity can be a highly effective tool for attracting and maintaining the interest of users on a web site. A visual change can draw attention to part of the screen, or indicate that a process is occuring, such as content loading. A sound effect can draw attention to a user action, or an event taking place. Both visual and auditory interactivity can make the experience of browsing a website richer for the user, by engaging more of their senses.

Optimization

bandwidth optimization

In order for a site to download quickly the graphics, code  and other content must be compressed and streamlined. Graphics software such as Adobe Photoshop or Illustrator can convert images to compressed formats such as jpeg, gif, or png. Over-compressing an image can cause a loss in quality, so it is a matter of choosing the appropriate format for the type of image and compressing it as far as possible while retaining an acceptable quality. Macromedia Flash takes a different approach: it is a vector graphics application which compresses graphics  by defining them mathematically. This can lead to a dramatically smaller filesize and faster performance of animations.

search engine optimization

If you care about being found in the search engines, your site's content should be search engine readable. Wherever possible, the content should also be described by metadata such as keywords, desription, and image and link names. Google ranks web-pages by their relevance to search terms so it is important that the content on a page is actually about what it is described to be. Attempts to spam the search engines do not generally work, and may result in blacklisting, so they are not worthwile. Links within the site should ensure that a web-crawler (program used by search engines to index the web) can traverse all the pages on your site by following the links. It is also worthwile to link out to other sites that are relevant to the topic.