To compliment tip 14 - Simplifying with Macros, I'm including the macros I use for my core abilities, Death Strike, Rune Strike and Heart Strike. I'm also including my Dark Command macro used for taunting.
Each of my macros starts with #showtooltip and the name of the ability. This forces the game to display the proper icon and the proper tooltip when the mouse hovers over the ability. Otherwise, the game defaults to the first ability within the macro which is often incorrect.
Feel free to leave a comment with additional macros that you've found useful in offloading the amount of things we Blood Death Knights need to keep track of.
#showtooltip Death Strike /cast Vampiric Blood /cast Blood Fury /cast Death Strike
My Death Strike macro opens by casting Vampiric Blood, which increases the amount of health received from healing spells and effects by 40%, which has a direct impact on the upcoming Death Strike itself - somewhere in the neighborhood of 6-7k additional healing for a T13 geared Death Knight. I've found that keeping up Vampiric Blood as much as possible reduces the burden on healers considerably.
Next, my Death Strike macro casts Blood Fury, an Orc racial ability that increases attack power by 1170. With a full load of Runic Power, Death Strike is easily one of - if not the - highest damaging abilities, so increasing the attack power for that melee strike helps the DPS output.
Finally, my Death Strike macro casts the actual Death Strike ability.
#showtooltip Rune Strike /cast Blood Fury /cast Rune Strike
My Rune Strike macro opens by casting Blood Fury. Just like with the Death Strike macro, I want to have my racial attack power bonus activated as much as possible. I then follow it up with the actual casting of Rune Strike.
/cast Blood Fury /cast Heart Strike
My Heart Strike macro looks just like the Rune Strike macro, casting Blood Fury and following up with the actual casting of Heart Strike.
#showtooltip Rune Tap /cast Vampiric Blood /cast Rune Tap
My Rune Tap macro steals a page from my Death Strike macro in casting Vampiric Blood for the extra 40% healing effect followed by Rune Tap, which converts one of my Blood Runes into 10% of my health, a net of almost 8k additional healing.
#showtooltip Dark Command /cast Dark Command /cast Blood Fury /cast Rune Strike
Unlike my other macros, my Dark Command macro actually starts by casting Dark Command in order to taunt my target onto me prior to following up with a Rune Strike. The rest of the macro is patterned right off of the Rune Strike macro … cast Blood Fury followed by Rune Strike for the largest possible hit.
It's worth noting this macro is a hold over from the days when Rune Strike was intentionally designed to generate lots of threat. It's not as important any more with the current threat generation model, and you could replace the Rune Strike with a Blood Boil, Death Strike, Heart Strike or almost any other ability. The point is to get a damaging ability off of the target right after it's been taunted.