One of the best things you can do as a tank, is to play a healer. I used to do almost only tanking, but once I got a few more 55s, I started doing other roles some. There are people better than you, and you can pick up tricks from them. I hit 50 back when LI Hm was fairly tough in group finder. Watching others tank the fights, I saw what I was doing differently, and what they were doing wrong. For instance sometimes standing in a certain spot can cause a healer to have to move or is just annoying in some way, but you will not know that until you try to heal that fight.
Other things, always build shield and absorb over endurance, endurance is pointless in most fights. Learn the fights before you try them, and look for tips to make the fights easier. As a tank, I would almost never have a mic step up with my guild when raiding and doing tfb hm before 2.0, but was still able to preform due to watching the fights, and doing the lower raids many times before. You are often expected to be the leader as a tank, so dont get angry, you can almost always take a group through a raid if they want to learn.
Basically, just know your stuff and watch others doing it, and make the fight as easy as possible for everyone else.