New LVL 15 class quests for Tank and DPS classes need to be added to better prepare players for instances by teaching them some best practices. They should not be allowed to enter instances before completing their class quest.

Tank Class Quest: Needs to have tanks mark targets for NPC to focus on. Also should teach tanks to regain aggro on mobs that break free from tank's aggro hold. If an NPC character dies, tank fails and must retry the mission.

DPS Class Quest: Needs to have DPS class focus on marked target, in numerical order, while paying attention to their aggro. Once aggro builds high enough, they should be forced to change to an alternate target while tank establishes better control. If the player gains aggro, NPCs should deal significant damage causing the player to die and fail.

Both classes should have to pass these LVL 15 class quests before starting and instances with other players.

I didn't add one for healers because I really have never had any fail healers.