Hm..for you, I would start unlocking all the new dungeons and start progress on wherever you left off on the main story quest.
Your goal is to unlock Brayflox hard mode. It shouldn't take you long but you need to find the quest giver. Many of them are stationed in Mor Dhona.
They did away with philosophy so here is how it works:
Tomes of Mythology server the purpose that Tomes of Philosophy used to.
Tomes of Soldiery serve the purpose that Tomes of Mythology used to.
You will always want to cap your soldiery weekly (450 per week). Hence, why you unlock Brayflox HM. You need to also unlock The Lost City of Amdapor, Halatali hard mode, and a few other dungeons to gain access to 'Roulette: Expert'. Roulette serves as a method to allow you to gain extra tomes of soldiery by sticking you in DF with 3-7 other random people in a particular dungeon associated with that particular roulette. I think I covered most of the ones in expert but you can find more information about the other roulettes online.
As I said, start doing the main story. You will want to unlock Leviathan at some point. Speaking of Leviathan, make sure you keep an eye out for extreme primals in party finder (a new feature added when you were away IIRC). This allows people on your server to set up a party for a particular mission/trial/quest/FATE/etc.
You are now able to queue in DF for Turn 1-5. I would say that Turn 4 has a really high success rate in DF whereas the others are hit or miss (miss on Turn 2 and Turn 5, somewhat of a miss on Turn 1).
Since you're i90, you won't necessarily need to farm items from those turns. If you've beaten Twintania, you are able to unlock the second coil as well.
My advice is to find the 2.1 and 2.2 patch notes. Look at the dungeons that were released and the location of the NPCs to unlock them.
Edited, May 7th 2014 10:25am by HitomeOfBismarck