Mastering Your Death Knight
The Death Knight is one of the best tanking classes in World of Warcraft, but unless a player has a firm grasp on the intricacies of the class it can be a frustrating class to play. For instance, the Blood tree is the only tanking tree available to a Death Knight, but the blood DK rotation can be frustrating to master. Add to this the fact that Death Knights do not get to use shields and we have a powerful class that in the wrong hands is a disaster.
The blood rotation is made more confusing because it changes based on whether you are attacking a single target or multiple enemies.
Let's take a look at the blood rotation for single targets. This will mainly be used on boss fights, whether that be in normal and heroic instances or on bosses in dungeons. Basically, whenever you only have one bad guy to worry about, this is the blood rotation that you use.
Single Target Blood DK Rotation
Now let's take a look at the blood rotation for multiple targets. You will use this rotation very often, especially as you grind out regular and heroic instances. Most of the instances in Cataclysm are literally filled with groups of trash that you will need to dispose of before you can get to the good stuff on the bosses. Mastering the blood DK rotation will make your life as a tank much, much easier.
Area Effect (AE) Blood DK Rotation
Both of these blood rotations are meant to be used as a tank. The blood tree is not a damage-per-second (DPS) talent tree.
I suggest that you head to the nearest target dummies and practice your blood Death Knight rotation before attempting to jump into an instance with a group. The blood rotation is not hard to master, but it will take you a few minutes to get your hotkeys setup and ordered so that you can tap them without looking while maintaining a vigil over the fight and your groupmates.
This blood DK rotation can also be used to level if you are the type of player who likes to be slow but sure as many of your talents will heal you as you kill the mobs in the game.
If you are new to the class then I suggest you take a look at one of the excellent WoW Leveling Spec guides that can be found on the Internet and grab a WoW Leveling Chart so you know where it will be best to quest.