Make sure to do your leveling roulette for that nice chunk of xp once a day. Also check your challenge log (hopefully you've unlocked it, I don't remember the quest but I don't think its too hard to miss), since completing those weekly challenges nets a decent chunk of xp as well. There's always doing fates and leves as well

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You could also try doing some palace of the dead. To unlock it, go to the inn in Gridania and do the quest "The House that Death Built" which will unlock it for you. Its basically a dungeon crawling minigame you can do with 3 other players. It doesn't matter what role you are and you don't technically need gear as it's provided for you. Every 10 floors you complete will give you a nice chunk of XP. It's also one of the better ways to level your alts later down the line so if you haven't unlocked it already you might as well knock it out.