Where to go on from here?

[Kaitlen]

After getting to 50:

1) Finish Story Line - Unlocks a bunch of stuff.
2) Unlock all dungeons so you can have access to the Expert and Hard Roulette Modes (gives Soldiery and Poetics currency, daily bonus)
3) Unlock Crystal Tower Series (24 Man/3 Team Raid)> Starting with Labyrinth of the Ancients (Crystal Tower) -- which will lead to Sycrus Tower and eventually World of Darkness (each drops currency and gear; iLevel 80, 100, 120 respectively) [you need a minimum iLevel to enter these and they also need to be cleared in succession] You may need to get some gear from the Market Board to get to a minimum level to enter these.

You'll need to at least get gear from the Crystal Tower and collect the currency (Poetics/Soldiery) to get better gear.

If you haven't already, you can start the Relic weapon quest as well.

That is the basics... and other people may have varying opinions on an exact path.

Coils: Coil of Bahamut, Second Coil of Bahamut & Final Coil of Bahamut (Turns 1 through 13) are the the endgame 8-man dungeons for the best gear in the game. (Final Coil is the latest release.... as where T1-T9 are showing their age.)

Sorry I don't have handy links offhand, but others can jump in and help out.

Secondary Stuff:
Hilibrand Quest Line - Unlocks Trials that are required for unlocking the Trial Roulette. (+ They are just fun. )
Extreme Mode Primals - Fun, challenging fights - Shiva is the latest EX mode; but you have to complete a few prior extremes to get to her.