My old WP theme was modified from the default template so there were many things I didn’t understand and left alone for safety.
Now I know
wp_head() action hook in header is necessary for trigger some plug-ins, same goes with
This book also helped me clean up my code now that I’m braver about writing my own functions in functions.php. The sections on [shortcode] is a good trick for text you have to repeat from time to time in a post.
For people who wants to build a responsive site to work on both mobile devices and on computers, the code to test for the device is way easier than what I’ve read in HTML5 and CSS3 books.
It may be too hard for a complete newbie (to WP and PHP) but if you have played with WP code and you need to do some serious WP theme building, start from Web Designer’s Guide to WordPress to learn how it works and how to work it.