DRK is fine.

There are just a few good tricks.

-use your CDs, normally, don't stack em
-pull with your rangeskill
-with Grp-Mobs, use your AoE 2-3 times then:
-use your Aggro rotation like this
1) 1skill on 1mob
2) 2skill on 2mob
3) 3skill on 3mob
4) 1skill again... now on 4mob
You know what i mean? Just "rotate" your aggrocombo, spreading it on all mobs like, skill, tab, skill, tab, skill, tab

You begin with low level so you can train a little bit, it's not that hard.

Look that you can oversee the enemies and your group. Best situation is like
You --> <-- enemies <-- Party