At least 2 resources that provide basic information about XHTML, such as what tags are available and what they do; formatting rules; or the separation of form and content.
At least 2 resources on CSS (although you will probably want more than 2). These resources could list CSS properties and values; the appropriate way to apply CSS to XHTML documents; particular text, image, or layout effects; tips on accessibility or standards-based design.
At least 2 resources that provide useful tools or information about color or design issues.
At least 2 resources for acquiring copyright-free images for use in non-commercial sites. (Tip: check outcreativecommons.org)