Ahhhh the EPIC Quest line!!
If you like to read the quests and actually follow their LOTR stories (like I do) then it's best to do them as they appear at your @ level. There is nothing more depressing than
walking through an Epic Quest where you are over-leveled and all the Mobs are "Gray" and ignore you. Sure you can do it EASILY but there is zero/zilch/nada excitement or fun. If the point of playing is to have a challenge & rousing fighting fun then why anyone would want to water down the main story line to a simple & boring walk through the park?
There are some Epic quests (and you will get a lot of them) you can do out of order (which seems strange to me but there you go.) {Ex. Do quests in Vol 2 when you're not done with Vol 1 or where you'll wave good bye to the Fellowship in one Epic quest but will have other Epic quests that take you back to talk to the Fellowship from where they just left.}
Some you can skip for a long time & others nearly have to as they are scattered across the land. However, you MUST complete the Moria Introductory Epic Quest-line (10 quests?) before you can enter Moria at @50th lvl.
As you level the majority will take larger fellowships to complete so with these the best way to do the whole EPIC deal is do the ones you can solo or with 1-2 others as they appear. Then all those that take a large Fellowship you let ride
until you can get a good group together and do as may of them as possible in a row.
One thing I found is, if you get a large Fellowship together for the Epic line you keep it going for as long as you can & complete as many Epic Quests (large fellowship sized) as you can: this might mean hours of game-time in one session (with the required Bio breaks in between). Getting a large group together for Epic's is not easy but once you have one together you want to get as much use & fun out of it as you can.
Epic Quests are usually "ID'd" by their number: ex. Volume 1, Book 3, Chapter 6 = 1.3.6 or someone looking for a group will say, "LFF for 1.3.6" LFF= Looking For Fellowship.
One thing that ruins a quest for me (and I avoid it now at all costs) is having an over-leveled player in the group. A player that can just run in and kill everything with one swing leaving you just standing around as he wipes out the entire quest mobs. Once again an exciting & fun quest turns into a boring walk past cool graphics & dead challenges.
Although- with the Epic Quests requiring Large Fellowships (or any such quest really) they may go gray on you before you can get back to doing them or find a large group. Depending on the day & time you play will determine how quickly & if you can get those groups together. As I said, if you get such a group going use it as long as you can.