General principles for good HTML design and implementation include:
HTML has its roots in SGML which has always been a language for the specification of structural markup. As HTML matures, more and more of its presentational elements and attributes are being replaced by other mechanisms, in particular style sheets. Experience has shown that separating the structure of a document from its presentational aspects reduces the cost of serving a wide range of platforms, media, etc., and facilitates document revisions.
To make the Web more accessible to everyone, notably those with disabilities, authors should consider how their documents may be rendered on a variety of platforms: speech-based browsers, braille-readers, etc. We do not recommend that designers limit their creativity, only that they consider alternate renderings in their design. HTML offers a number of mechanisms to this end (e.g., the alt attribute, the accesskey attribute, etc.)
Furthermore, authors should keep in mind that their documents may be reaching a far-off audience with different computer configurations. In order for documents to be interpreted correctly, designers should include in their documents information about the language and direction of the text, how the document is encoded, and other issues related to internationalization.
By carefully designing their tables and making use of new table features in HTML 4.0, designers can help user agents render documents more quickly.