Main Story Quests

Yeah, you're going to have to do a lot more grinding on your 2nd/3rd/etc classes. Unless they add more quests outside of the ones in your starting area there won't be many to do after that. the Hunter's Logs are a really nice way to gain EXP as well. You have to kill 5ish of a couple types of monsters and you get a big chunk of EXP. after you complete all 10 logs in a Rank you get another, larger, EXP chunk. I gained nearly a full level doing the three logs that required you to do a dungeon and finishing off the whole Rank 2 set.