Although I'm personally a web designer in my full-time job and as a side freelancer, it helps a ton for you to learn basic princples to either create your own themes, or better communicate with your designer(s).

We talked about a few principles of general good design, which also apply to web design:

1. Contrast—make it the same or make it drastically different. Contrast by:
   1. Size—at least 1.5 times difference, I prefer 2 times difference
   2. Color—don't get crazy, try using a theme color in your headers
   3. Font (use caution with different fonts on the web, but can use Typeface.js, sIFR, or FaceLift)
   4. Special effects (only use one special effect, and very sparingly)—often require Photoshop or similar image editor, paint.net and photoshop.net are great and free
2. Repitition—give you site a consistent look. Don't try to make every page look different
3. Spacing—sometimes called "white space," make sure you don't cram your information into boxes or "above the fold" (a concept in which I don't accept)
4. Relevance—somewhat related to spacing, keep connected information together, unconnected information separate. Also make sure that you don't move important stuff like your logo and navigation to weird places, even if they seem really "cute."
5. Knowledgable recognition—once you know about some basic design principles, you'll spot it more often. Keep these in a folder, even if you just like one aspect of a design, to help you refine you understanding of what makes good design.

Additionally, we discussed:

• Differences between JPEG, GIF, and PNG image formats.
  • JPEG for photos
  • GIF or PNG for images with solid colors. PNG was made to replace GIF, but PNG supports true transparency in modern browsers (which means almost everything other than Internet Explorer 6)
  • Also talked about some different applications of transparent PNGs to create color, corners, text, and more.
• My opinion is that Internet Explorer 6 and 800x600 screens are dead, so we shouldn't have to worry about them.
• Some themes are programmed well enough that you can modify colors and images within the WordPress admin interface, others may not.
• Some live ctriquing of sites and themes to see how well they worked or not.
• Revolution and K2 are good themes either out of the "box" or starting points for customization

Two of my personal websites, built on WordPress:  the Ramen Noodle & Are You Just Watching?