Welcome back!

You can really do whatever you enjoy. There are many different ways to acquire gear satisfactory for raids, so the best choice is just whichever you find to be the most fun. Once you reach 70, you'll be able to earn two new types of tomestones: creation and mendacity. Creation can be used to get 330 gear; Mendacity can be used to get 360 gear. Dungeons can now drop gear all the way up to 345. Alliance raids can now drop gear all the way up to 360. You'll also be handed a set of 290 gear for completing your level 70 job quest. Eureka can upgrade that to 350 (355 for the weapon). The easy story mode version of the 8-person raids drop gear up to 350, too. And the tomestone gear can be upgraded to 340 and 370. So ... yeah, just do what strikes your fancy.