Well, I will take my shot at advice. I am not the world's greatest tank but being a tank nowadays is not a huge deal.
Anyway....
The most obvious thing to do is take all the Tier 1 tanking talents and then pick a tree after that. You want to balance DPS talents for TPS with Tanking talents. Blood has the advantage of extra health, Frost of more passive tanking talents, and Unholy is the anti-magic tank (with pre-3.2 UB excellent for AE tanking).
I have tanked as Frost and had no issues with threat. One mechanism that can be very useful is to put a point in DeathChill and use that with an Howling Blast to pull. Should give pretty effective AE threat to start. If you Glyph HB, you get AE Frost Fever going.
Blood has the advantage of the extra health and the downside of AE issues. That is not horrible on most boss encounters but basically D&D is your AE and that eats lots of runes.
Right now the "EH" (enhanced health) tank is the way to go, especially as the way to get started on an encounter. That would be a Blood Tank (Veteran of the 3rd War + Vampiric Blood). Given that you want to get Vampiric Blood and probably Improved Death Strike, the only question is do you go much deeper in Blood (Blood Gorged for example makes little sense). 3/3 Morbidity will probably be required (to get the cooldown reduction on D&D). How many self-healing talents is up to you.
If you look at my profile right now, I am running a high self healing build for pvp. I use this build to tank with as well, and one could easily optimize it more greatly for that.
http://www.wowarmory.com/character-sheet.xml?r=Trollbane&n=Merryanne