So here are some online resources I plan to work through:
I probably should already know a lot of this, but best go through & check : http://docs.webplatform.org/wiki/concepts
I should try doing more of this on the next Wordpress site I build : http://www.netmagazine.com/tutorials/getting-wordpress-play-nice-responsive-images
I should work through these too: http://www.codecademy.com/learn
At some point I'd like to do these : https://www.udacity.com/
These are paid-for, but seem nicely problem-oriented and are more designery and less code-y
http://www.lynda.com/Design-Page-Layout-tutorials/Before-After-Things-Every-Designer-Should-Know/110285-2.html
http://www.lynda.com/CSS-tutorials/CSS-Gradients/115467-2.html
http://www.lynda.com/course-tutorials/Choosing-Using-Web-Fonts/97715-2.html
Plus possibly :
http://www.lynda.com/PHP-tutorials/Debugging-PHP-Advanced-Techniques/112414-2.html
http://www.lynda.com/Git-tutorials/Git-Essential-Training/100222-2.html