Veneretio posted a back to basics post on his blog. I think everyone who has ever or will ever tank should read it because even though he is giving warrior advice most of the stuff he talks about will help any tank (except maybe bears but some of the stuff is good for them too). I really liked the last paragraph of his post because I really think its the most important part.
You haven’t really talked about Gear
You’re right. I haven’t. Tanking is more about how you use your gear than the gear itself. So, training yourself in how to tank, how to enchant, gem and spec are all more important than how to find the loot you want. The reality is once you start raiding, you aren’t going to get exactly what you want. You take what you can get and you make the best of it.
His blog is always a great read and very informative and has really helped me be a better tank even though my rage bar is blue and not red ;)