first timer

So I think I've been playing WoW for about 1.5 years now. I have never tanked. Seeing the abuse heaped upon tanks should any error occur pretty much kept me away from that! However the recent changes to lfg and the obvious shortage of tanks (including my guild) has made me rethink that. I have been trying to decide whether to go with the dk or the warrior. By default, the warrior won as he had more tank gear. I spent a good part of yesterday reading about glyphs and spec and things of a tanky nature. Got my troll geared. A few purples, mostly blues. Got the numbers. Hotkeyed some talents. Got "omen" (although I have no idea how it works yet!). Decided to start easy and queued for H VH. Took all of about 1 second and I was in. Let the group know it was my first tanking ever and that I was appropriately geared. One dropped, the rest hung in and we went at it. Things went very well! I held aggro at all times. I don't think that's saying alot with VH, but that is the reason I chose that instance. My healer let me die a couple times, but no wipes so it was good. I'm doing glyphs of blocking, sunder and cleave, with the idea that that will give me better aoe aggro (less target switching). Now, devastate is better than sunder due to the damage effect, but my question is does glyph of sunder armor work when I use devastate? Gonna have to check on that. Otherwise I guess I'd be better off with glyph of devastate. Any other ideas? Basically I wade in, demoralizing shout, maybe a thunderclap, devastate (use revenge and SS in between). I've also been putting a rend on mobs with the assumption that the dot would help with aggro although I don't know how much truth there is to that. I'll try some of the easier heroics today and we'll see how it goes!