If diseases fall off, replace SS1 with IT/PS to reapply them. Open fight off with IT/PS instead of SS1.
Keep Ghoul Frenzy up at all times. The best way to do this is to use blood tap after the death runes from blood strike have faded. If blood tap is down use ghoul frenzy with a death rune and icy touch and then fall back into your rotation.
To dump runic power, use unholy blight. If that is already up, use death coil. Use runic power when your next attack will push your over 100 runic power.
Use gargoyle when you are high on runic power and you have as many buffs as possible up. This means use trinkets beforehand along with timing it with raid buffs because the gargoyle will use your stats at the time of the summon to calculate it's damage for the whole duration.
If you have blood runes, use blood strike ASAP to turn them into death runes.
Talent Calculator - World of Warcraft
Variations on this spec include:
Taking 2 points out of Necrosis, and putting them in improved unholy presence. The movement speed is situational.
Morbidity is also a personal choice. If you don't think it's worth it, you can move the points to necrosis.
Any extra moved talents should be spent in dark conviction after necrosis is maxed out.