For the rules and tips for composing, see the HTML Cheat Sheet.

You can get help with html problems with the alt.html newsgroup. The FAQ for the newsgroup is also a useful source of HTML information. For CSS, use a different newsgroup: comp.infosystems.www.authoring.stylesheets.

Dreamweaver is the tool most professionals use to edit HTML.

Six Apart MoveableType and CityDesk are tools to allow a team of people to collaboratively maintain an rapidly changing website.

Editing HTML is somewhat more complicated when in has embedded Javascript, JSP or Freemarker, XHTML, XML. Before you buy an editor check how well your tool deals with the complications you will be dealing with. Profession web design is focussed around CSS style sheets. Make sure it handles those effortlessly.

If you are curious how I created the HTML for this website, see HTML static macros.

For HTML to be compressed, the browser must send a Accept-Encoding: gzip header to indicate it in prepared to accept html.gz files. Otherwise the server will send it the fluffy version.