Howling blast -> Plague strike -> Blood strike
(Sometime you get lucky with proc's and don't need rune recovery from blood strike but be prepared).
1) Killing machine -> Frost strike (Learn to recognize UI animation)
2.)Keep frost disease running -> Howling blast
3.)keep blood plague running -> Plague strike
4.)Rime -> Howling blast (Learn to recognize UI animation)
6.) Howling blast
7.) Blood Srike (Locked out because you have no runes left ^-^ )
**Obliterate: For low gear levels go onto heroic target and check the damage of obliterate versus howling blast. If howling blast is significantly higher than obliterate ignore obliterate. Obliterate scales mainly off weapon damage while howling blast scales off AP so at low levels HB often does alot more damage than obliterate and can be ignored as it basically just gives free HB's via rime.
CLC_DK addon is useful if you want a visual queue on screen.
AOE: Is similar to above except no obliterate its just HB spam and you are usually using D&D every CD.
** Remember Warcraft players fail in directions you never thought possible.