I was hoping is someone can give me tips on how I can do good DPS on my DK. I got myself a DPS add-on and by looking it at I seem to be only around 4th on the list while everyone else is way higher then what I seem to be. I am not sure if the talents I use are set right for DPS or if it is the gear I have or the combo I use...

The combo I do currently use is something like
Frost Strike, Plauge Strike, Death Strike (when ever I can till I need to redo the other two), Blood Strike and then Death Coil if everything is on cool down.

My talent tree is something like 50/4/26

If you want to look my char up on the wow armory his name is Zathos and I play in khaz'goroath ( say this cause I am not able to post a direct link myself as I posted this from my phone).