Tanking as a Dk.

I've gone fully from healer to a DK tank, and its been a learning experience... I do great at AoE tanking but it seems I fall apart at single target, I don't know if it is my spec or maybe my rotation is weak for single target... but I'm dieing to figure it out......

I mean is there some attack that DK's have that can really front load the threat over a bunch of hair trigger dps that would run ahead of the tanks if we didn't keep them on a leash? and seriously would it kill some dps to wait a moment before whapping a target before it gets to a tank..... really dps........ Dead dps doesn't ya know dps....... can't kill the boss if your killed.... It shouldn't be numbers people it should be getting the boss down.