So you hit 50....what next? Well you could level an alt, hit crafting up or you might want to progress towards end game. If you do want to gear up, then AK will be somewhere you spend a lot of time! This is the level 50 instance that drops i-level 60 gear, and gives you tomes of mythology and philosophy. Philosophy tomes are handed in for Darklight gear which is i-level 70. The two ways people tend to farm tomes is either in AK (especially if you need other gear sets which have a chance of dropping) or by doing speed runs of Castrum.
AK gives you 120 tomes of philosophy and 40 of mythology. Mythology tomes are capped at 300 per week, but you can farm as much philosophy as you like. AK is a 4 person run, while CM is 8 person.
Philosophy tomes may be handed in for gear by visiting Auriana in Revenant's Toll.
Forming groups within the FC , and chatting on raidcall is by far the best, and most fun way to run this content. If socialising and meeting fellow fc-ers is not your thing then you can always shout in Revenant's Toll, and find groups with players on the server. Or try your luck with duty finder.
AK used to be able to be done by way of speed/tank death runs, but a recent patch made it a more conventional instance. Some videos you watch may have the old speed run strats, but the boss fights should be the same strats.
I guess what I am getting at is that the more people who hit 50, the easier it will be to form FC groups. Gibsauce/Phobos and I run this at 1.30am Pacific time most weeknights. If anyone in that timezone feels like dpsing for us, feel free to shhot us a tell and we will be sure to include you :)
As well as all that, there is a relic weapon quest chain to work on. I found this Sheephead video really good for advice on endgame gear progression. The only thing i did different was to skip the Grand Company weapon and farmed Ifrit to get one from him instead. This can take a few (or maybe 30!!!) runs if you are a WHM or BLM. Everything else seems to drop frequently.
http://www.youtube.com/watch?v=QcvlrmhjcOQ