The Empire of Zul'Drak

Begin the zone by picking up quests from Elder Shaman Moky, Chief Rageclaw, and Crusader Lord Lantinga at Light's Breach, taking on This Just In: Fire Still Hot!, Trolls Is Gone Crazy!, and In Search of Answers simultaneously to knock out multiple quests at once.

Watch your inventory for Strange Mojo, which is a dropped item that starts a chain of 27 quests beginning with Strange Mojo and running through Precious Elemental Fluids, Mushroom Mixer, Too Much of a Good Thing, To the Witch Doctor, Breaking Through Jin'Alai, To Speak With Har'koa, and many more — missing this chain is a common reason players get stuck around 63/100.

Kill Scourge enemies to obtain either the Unliving Choker (Alliance) or Writhing Choker (Horde), which starts a second major drop-based quest chain that contributes significantly to your quest count.

Pick up The Champion's Call! as a lead-in to the Amphitheater of Anguish chain, which contains six quests — completing this line alone can push you past the 100-quest requirement without entering any dungeon, and dungeon quests themselves do not count toward this achievement.

If you finish everything above and are still short of 100, tackle the remaining group quests — WANTED: Ragemane's Flipper (group of 3), Malas the Corrupter (group of 2), The Gods Have Spoken (group of 3), and Convocation at Zol'Heb (group of 3) — all of which can potentially be soloed at higher item levels.

Complete Feedin' Da Goolz before turning in Betrayal, as it becomes unavailable after that point; similarly, pick up The Champion's Call! before progressing too far into the main chain, as it is a timed breadcrumb leading to the Amphitheater of Anguish line.