Affliction Warlocks rotation revolves around keeping curses up on the target and using drain soul at and below 35%. Affliction Warlock has great sustained DPS ramping up along the fight, however for really short fights the damage can be low.

Rotation for Affliction Warlock Wotlk

Affliction Warlock Priorities

Curse of The Elements (If no other spell buff is present) > Shadow Bolt (Keep debuff on the boss) > Unstable Affliction > Haunt > Corruption > Curse of Agony/Curse of Doom (If there is another spell buff present) > Shadow Bolt/Refresh DOT’s >  Drain Soul on 35% HP

Tips

Keep the DOT’s on the target if the fight is lasting for more than 30 secs without clipping, when the boss reaches 35% there is no point on refreshing DOT’s.

Balance Druids and Unholy Death Knights can apply the bonus 13% spell damage, if neither is present Curse of Elements takes priority.

In a boss fight Curse of Doom or Curse of Agony end up neck to neck in terms of DPS, plus the 24 secs to 1 min will allow the use of extra Shadow Bolts or refresh of other DOTs, so it can ease up the rotation and keep the DOT longer especially on the burn phase.

At the end of a cast, an instant spell can be cast without occurring GCD, this is true for every cast/instant sequence, should be used to maximize DPS.

Use CDs when there is barely any movement or crowd control effects to maximize DPS, the best way to do this is by knowing the fights and use gateways to minimize movement.