Why do we need to know HTML? Isn’t that why we have Dreamweaver and GoLive? If you know how something is built, your designs will be more informed since you will know what is possible. Most visual editors write terrible or bloated HTML code, which can be a pain to understand and maintain. If you see an effect on someone’s site, you can understand how they did it – and recreate it for yourself.

The Web is not Paper! Embrace the differences, and go with the flow. Basically, you will find the easiest time if you specify the widths of things, and allow the heights to be determined by the Web browser. Be aware that users can override many of your design decisions, too, which suggests the need for flexibility that is not needed on paper. The browser and computer environments for users vary so widely that you must take this into account. Pixel-perfection leads to madness.

Choose – don't fall into a Web coding style. There are lots of ways to skin a cat. Understand the differences between the Old Way (Tables) and the New Way (DIVs and CSS).

I cannot emphasize enough the importance of syntax and good typing. 90% of the errors that beginners make are either from typos or misapplication of the rules of HTML syntax. These are both alien concepts to non-programmers: (1) that you must type accurately at all times, and (2) that all of the picky details of syntax must be correct, especially including commas, semicolons, colons, and quotes. Validate your HTML and CSS!