Something that I've found is severely lacking when someone joins a server is a lack of connection to community. The first few weeks can be excruciating for a new player, not only because its a new game that they don't know, but also because they don't understand the many tools that are uniformly used for finding kinships, finding fellowships, understanding channels, etc.
1. One thing that might help boost a new player's ability to interact upon joining a server would be an interactive and re-playable tutorial "a little like the big battle tutorial in Bree" where a NPC would help a player learn how to use Instance Finder, Certified Chat channels, Social Panel, Fellowship Finder, etc. The NPC might do things like force them to learn how to ask/answer questions in /Advice, etc... Even give them a quest to deliver an item to another social NPC at the 2nd quest hub. i.e. Combe, Gondamon, Tuckborough, etc... where that NPC can remind them of what they learned, and give them a recurring quest to go back to the original NPC via a story line.
2. Another thing that would help is to change quests so that they can be re-done, even for no/little experience. For example, in instances a player can complete the same quest over and over again, but generally only 1 time on landscape. If you change the quest log so that, when in fellowship with a player, you can see which quests they are doing (even though you don't have the quest yourself, or have already completed it) you can jump right in and help that player do them. Maybe make an option for "Reaccept Quest." For example, a lvl 12 player in Staddle, doesn't know how to get to the marshes, or is a RL friend of a level 95 who is playing. The level 95 could fellow them, see which quests they are doing, accept the quest long ago completed, and partner with them for the content. The 95 will not get xp credit for the second quest, but can mentor / play with their friend regardless. I often see players cry for help in the wilderness of the Trollshaws, but since an upper level has already completed the quest, its a huge hassle to help someone where you can't even accept/read their quest dialogs. I could see this being a problem for phasing technology in the new areas with missing NPCs, etc... or make it so that NPCs phase in for quests when shared.
If I recall correctly, new players only get the 1 pop-up window for guidance, and if they select, "do not show this again" the advice disappears forever. Considering every menu has this pop-up as a new player, it would be helpful to make this a more interactive / and re-playable experience to help new / returning players get up to speed. From my own experience playing MMOs, I usually spend the first 5 hours figuring out stuff, and pop-up windows only help you retain their knowledge for limited duration when you're already overwhelmed by everything else happening.
Also, for returning players who have not logged in for months/years, maybe enable a "welcome back" series of pop-ups to help get them back up to speed on the GUI, maybe even port them back to archet etc for the tutorial. I often see players coming back after years away who have to spend days just trying to remember how to do the basics. Often get aggravated that they don't remember/recognize the changes to the game, and they leave again.
The quicker a player can get connected to another player for help, or be reminded of what is happening after many months / years away from LotRO, the more likely we are to retain their interest in this game. Enhancing, reminding, and retaining population should be a key goal of Turbine going forward.