Here’s a list of WordPress and CSS resources that helped me get to where I am today in WordPress themes development. The following links are listed in no particular order.

• Faux Columns (by Dan Cederholm)
  Your main column and sidebar column backgrounds aren’t even? Faux Columns is the answer.
• Max Design CSS Tutorials
  Styling WordPress is mostly styling lists. Max Design tutorials are the best place to start.
• Sliding Door (by Douglas Bowman)
  For an advance horizontal menu, learn the sliding door technique. WPDesigner’s current top menu bar is the result of Sliding Door.
• Dynamic Menu Highlighting
  After learning the Sliding Door technique, take it a step further. Learn how to highlight your menu tabs.
• Tizag PHP Tutorials
  Creating a WordPress theme doesn’t involve just XHTML and CSS. You need a bit of PHP knowledge. I like Tizag.com’s detailed tutorial on the If / Else statement the most.
• WordPress Lessons
  Read my tutorials? Ready to move on? At the end of the day, there’s no better guides than the lessons from WordPress.org showing you the ins and outs of a WordPress theme.
• Lorelle.WordPress.com
  To learn even more about WordPress, design, and development, visit Lorelle on wordpress.com.
• Designing Themes for Public Release
  Want to create and release your own free WordPress theme? Read Designing Themes for Public Release first.

The last and ultimate resource is curiosity. I keep learning in order to improve my methods and techniques so I can create better WordPress themes at a faster rate.