If you already have written hard copy it's tempting just to reuse it on your web pages. This is a mistake - reading a web page is not the same as reading hard copy and your content should be rewritten to be suitable for the web.
Many users flinch if they see long paragraphs. It's best to strip your copy down to the bare minimum required to get the message across then break it into small chunks that can be read quickly and easily.
Use headlines and sub headlines above blocks of text to summarise the content. This allows users to cherry pick the information that they're interest in.
Lists with bullet points are useful for separating out the features or benefits of a product or service and make decisions easier for users.
Try to place important content "above the fold". This refers to the area of the page visible to users without vertical scrolling.
Text Style
Use text style consistently. Inconsistent use of capitalization, bold or italic for emphasis can confuse users about the relative importance of phrases - and looks unprofessional.
For example on navigation, if you have a link that says "About Us" then a link "Contact us" the capitalization is inconsistent. This should also apply to headlines above blocks of text.
Avoid using all uppercase letters or use them sparingly. It makes text harder to read and appears as though you're shouting at the user. Overuse of uppercase, bold, italic or colour for emphasis will end up emphasizing nothing.
Never use underline for emphasis in plain text - users will mistake it for links and become irritated when nothing happens when they click it.
Avoid using lots of different font faces, font sizes and font colours on a page - it's difficult to read and looks unprofessional. Try to use one font style throughout the site with perhaps one other to highlight particular areas.
Use sufficient contrast between background and text. A white background with black text is the safest option.
Site Tools
Tools that allow users to calculate prices etc. are useful and should be considered if relevant.
Don't provide tools that are not related to the purpose of your site just because they're available - they take up valuable space and are a distraction.
Don't provide tools that replicate functions of the browser, such as add to Favorites - users can do this for themselves.
Advertising
There are advantages and disadvantages to advertising on your site - consider the balance carefully.
If you display image ads then try to have only one on each page and label it as an advertisement.
Try to avoid mixing ads with important content, as that content will tend to be ignored.
Avoid making your own content look like ads or it's likely to be ignored.
Of course if you actually want people to click on ads, and you may, then do the opposite to above.
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