Pretty new to this tanking thing as i used to be dps, im just looking for a little more direction then what i have now, ive kinda guessed at gear and other things so advice would help a lotThe World of Warcraft Armory
Okay... where to start. Try to find a cookie-cutter frost spec, you can see mine on my armory, I think. It's not cookie-cutter, but it'll do.
Replace all your gems with either 24 stam or 8 defense rating/12 stam. 8 dodge rating/12 stam will also work for red slots (with stamina socket bonuses). 8 strength/8 defense rating is not too beneficial. Replace all your enchants with pure +stam ones, +22 def to chest, +16 def to cloak, and either armsman or 18 stam on your gloves, depending on how your threat is. Do Heroic Azjol-Nerub for the trinket to replace that green, and remember that tanks need the best enchants, the best gems, and require (arguably) the most research to succeed as. DK's are definitely strong tanks, but they do require skill and knowledge to be efficient. Make sure you read up on everything and practice a lot, and don't get discouraged. Good luck!
Any basic tanking spec should start with 5-5-5 foundation. 5 points in Blade Barrier, 5 points in Toughness, 5 points in Anticipation. Annihilation is the talent that puts together your frost rotation; Frigid Deadplate and Rime are talents I would not skip for a frost tanking spec.
Check out my DK's frost spec also if you want to get an idea of a basic frost tanking spec.
U can lose 10 from def, to 540 or even 535 for heroic 5 men, as all above 540 is useless and u need to build up hit and expertise up to minimum of 5%.
Defense continues to be useful after 540. That threshold will remove critical hits from NPC's, but it will continue to provide avoidance and increase the effectiveness of IBF.
Miagorme and Molohk have already covered the major points for enchants and spec. I just wanted to clarify the defense 'cap' comment. About the only thing I can throw in beyond that is that bladed armor is likely to prove the most efficient off-tree threat increase for deathknight tanking, due to its large contribution in frost presence. If you can afford to pick that up after reallocating points for mitigation, you'll see some high threat returns.
My Frost spec is pretty standard, you can agrue over Death Chill, Morbidity, Litchborne (works wonders with the cat lady though) and Icy Talons; but all in all it's pretty basic. Enchants and gems are pretty standard too.