What are some of your best tutorials for PS?

What I mean by that is, I'm looking for shadowing help/technique ..etc.
I notice that I'm sort of all over the map when it comes to shadows -maybe I'm too hard on myself and they are fine, but I know there are tricks.

If you have any other help links or even tricks for other techniques (that you use quite often) I'd love to hear 'em.

I know I should of dug through the forum to see if there was already a thread started re: this type of question but... I didn't. So ... please and thank you!

(p.s. if you know of an active thread that does have this sorts of help please link! I know of one, but I like to have more than just one source, if ya get me.)