By the book
'Research-Based Web Design & Usability Guidelines' on:The home page
A well-constructed home page will project a good first impression to all who visit the site.
It is important to ensure that the home page has all of the features expected of a home page and looks like a home page to users. ... A home page should clearly communicate the site's purpose, and show all major options available on the Web site. Generally, the majority of the home page should be visible 'above the fold,' and should contain a limited amount of prose text. Designers should provide easy access to the home page from every page in the site.Page layout
It is usually a good idea to ensure that the pages show a moderate amount of white space ' too much can require considerable scrolling, while too little may provide a display that looks too 'busy.' It is also important to ensure that page layout does not falsely convey the top or bottom of the page, such that users stop scrolling prematurely. When a Web page contains prose text, choose appropriate line lengths. Longer line lengths usually will elicit faster reading speed, but users tend to prefer shorter line lengths.Headings and titles
Most users spend a considerable amount of time scanning rather than reading information on Web sites. Well-designed headings help to facilitate both scanning and reading written material. Designers should strive to use unique and descriptive headings, and to use as many headings as necessary to enable users to find what they are looking for ' it is usually better to use more rather than fewer headings. ... Designers should ensure that each page has a unique and descriptive page title.Images and graphics
When used appropriately, graphics can facilitate learning. ... When used appropriately, images, animation, video, and audio can add tremendous value to a Web site. ... When images must be used, designers should ensure that the graphics do not substantially slow page download times. ...
Sometimes it is necessary to label images to help users understand them. Usability testing should be used to help ensure that Web site images convey the intended message.Navigation
Create a common, Web site-wide navigational scheme to help users learn and understand the structure of your Web site. Use the same navigation scheme on all pages by consistently locating tabs, headings, lists, search, site map, etc. ... Make navigational elements different enough from one another so that users will be able to understand the difference in their meaning and destination. Grouping reduces the amount of time that users need to locate and identify navigation elements.Links
To ensure that links are effectively used, designers should use meaningful link labels (making sure that link names are consistent with their targets), provide consistent clickability cues (avoiding misleading cues), and designate when links have been clicked. Whenever possible, designers should use text for links rather than graphics. Text links usually provide much better information about the target than do graphics.The appearance of the text
Black text on a plain background elicited reliably faster reading performance than on a medium-textured background. When compared to reading light text on a dark background, people read black text on a white background up to thirty-two percent faster. In general, the greater the contrast between the text and background, the easier the text is to read.Organizing the content
Organizing content includes putting critical information near the top of the site, grouping related elements, and ensuring that all necessary information is available without slowing the user with unneeded information. Content should be formatted to facilitate scanning, and to enable quick understanding.Writing content for the Web
When preparing prose content for a Web site, use familiar words and avoid the use of jargon. If acronyms and abbreviations must be used, ensure that they are clearly understood by typical users and defined on the page. Minimize the number of words in a sentence and sentences in a paragraph. Make the first sentence (the topic sentence) of each paragraph descriptive of the remainder of the paragraph. Clearly state the temporal sequence of instructions. Also, use upper- and lowercase letters appropriately, write in an affirmative, active voice, and limit prose text on navigation pages.
You can download a copy of 'Research-Based Web Design & Usability Guidelines' at www.usability.gov.