1. Get to level cap. Complete all normal first-tier dungeons before you unlock any first-tier Heroic dungeons.
2. Complete all first-tier dungeons on Heroic before you can zone into the first raid tier (Heroic or normal) or second-tier dungeons on normal.
3. Complete the first tier of raids to unlock the second tier of raids and complete the second tier of dungeons on normal to unlock those same dungeons on Heroic.
Simple even stepping-stone to make sure that everyone in Heroics has seen that dungeon – and all other dungeons – on normal on that character before they’re messing with Heroic modes.
Make sure that there are weekly raid quests for old-tier raids so that someone who comes to an expansion kinda late has a chance to “catch up” to their guild. Weekly raid quests should never be for “current” tier content, always for old, easy stuff. No-one should ever have to wait more than a week or at most two, for their guild to do a run through an old tier to complete the weekly raid quests and incidentally get someone’s alt or a new raider keyed up.
4. Every time you defeat a tier’s end boss you get a BoA libram. That libram can be used to unlock that difficulty and everything of lesser difficulty for one of your alts.
Gets new people a chance to see more content. Makes more people appreciate all the hard work and the storyline of each expansion.
Pisses off a few hardcore raiders.
No rep grinds to unlock stuff.
No specific drops or annoying quests that require you to run back and forth. Just kill the end boss of this or that and now the character you’re currently on is ready for the next step, while one of your alts is ready to step into the stuff you just completed.