1-15 adventures plains (quests)
15-25 valley of Luxem tower (quests)
25-35 zant (quests)
35-45 breezy hills (quests)
45-55 anima lake (quests, get a sweet level 50 armor set with 10% exp gain that can be combined with costumes)
55-60ish Junon polis (quests)
By this point you should be able to move to kenji beach and either just kill or do the quests there for exp and Zulie (if you need it) after that you can move to gorge of silence or move onto Luna to try to exterminate the cute bears in mana snowfields, if you can't quite finish them you can always back track to the other maps looking for the npcs named coffinton, they have some nice repeatable quests for exp they do get repetitive and boring though. By the time you're done there you should be pretty close to 100.
Hearts and crystals are for crafting gems, runes are for equipment crafting, powders and lisents are for refining
Union quests are called valor quests now, each corner of Junon polis has two npcs with the respective Union names above their heads. One of the two I think normally the left ones have quests you can grab at anytime (there are no Union restrictions anymore).
Oh and if you mess up your character at level 50 you get a free skill/stat reset from the mayor in Junon polis.
Edited by Zurn, 24 February 2016 - 06:34 PM.