Let every account log in twice.
People could rez themselves with any account with a high cleric paladin and would be encouraged to keep one account going to cacth up those lower people they never got around to level up because they are on the same account as that Druid or whatever you think is good to help others P-level.
Faster XP - 4x the current rate would be about right 6x for people under level 40. Reactivate the quest to create double XP potions too so peolpe can even double that rate if they like and make the quest drops for that quest much easier to obtain.
Reduced death penalty - 1/2 current would be about right.
Easier soloing. Make every class capable of soloing to level 70 if they choose to do so. Stronger pets, double the effects of armor, double the damage done by people, half the damaeg done by monsters. Make mobs drop 5x their current plat.
Recognize the genius in the World of Warcraft ability to Make most raids doable with a Five-Man! make "Almost" every item in the game possible to solo or obtain with a single six-man group. The days of the great raid or winding down and the only thing that will save the game is the comeback of the casual players to boost the ranks. You've done an awesome job of driving them out, now try to bring them back.
Put ALL spells on vendors. Period.
Add the equivalent to the Warcraft Battlegrounds where people are sucked into groups from anywhere in the world by an automated Queue system and have FUN - end the LFG LFG LFG cycle that killed the game in the first place.