The problem with that is there's really nothing I can teach you that these can't. Most of what I know comes from tutorials and self-teaching, but unless I were to make a tutorial (which would be pointless since everything I know is already IN a tutorial somewhere), then I can't give you my own experience. And frankly I just do not have the time to do almost ANYTHING I want to do anymore, let alone make a tutorial. So, sorry, you're gonna have to settle for this until maybe I try my hand at tutorials someday.

Really though, the best advice I can give you is to just experiment and figure some stuff out on your own. Still follow some guidelines in tutorials and such, but adjust them with your own variations here and there. You learn something by doing it a lot more than you learn by reading about it and copying it. That does mean you're gonna mess up on stuff a lot, granted, but you'll have to get over that to make any progress. That's kind of a universal rule for all art forms.

http://purplekecleon.deviantart.com/art/How-I-See-Color-A-Tutorial-184642625

http://darkersounds.deviantart.com/art/Fire-Shading-and-Lighting-Tutorial-Part-1-313296019

http://tamarinfrog.deviantart.com/art/Making-of-RD-Comic-188548270

http://tamberella.deviantart.com/art/Giant-Shading-Tutorial-251104611

There's TONS more tutorials out there for just about anything you'd ever want to know; this is just a handful of some that I refer to often. It might not be a bad idea to just take a day to find a bunch more and save them where you can look at them when you need to.