In a tutorial?

I want you to post what sort of things you want to see in a tutorial. I plan on making a tutorial similar to the one I have stickied in the tutorial sections. I was wondering if there were any specific areas in which you'd like me to go in-depth in. Right now I plan on doing a section on composition, colours, depth, lighting. For me they are the core principles, so I want you to give me some ideas on what else I should cover. Ive been thinking about doing a section on Art Theory but I'm not quite sure on its helpfulness and how it can be implemented seamlessly.

So any ideas?