Leveling up low leveled battle classes a HUGE issue at moment.

[Kerii]

The greatest asset in this game is other people. You don't want to mindlessly farm the same content again and again? Make friends.
You don't want to pay extremely high prices for things on the market board? Make friends.
You can't stand the duty finder and the party finder scares you? "MAKE FRIENDS!!"

I realize this sounds like common sense, but people in this game are so obsessed with the best and easiest ways to do everything they forget their greatest resource. Aside from that... I'd chime in that fates should only be done with friends, it's more enjoyable that way. Leves are actually "great" exp once you find the farmable one or two in each group. Hunting Log is basically instant 15 if a lv50 friend OHK's them for you.

Edit for clarity: You "do not need to be in a party to get decent exp from fates" I just found it more enjoyable. I've done enough fates on previous characters for two other people's atma (Pre nerf), and my own for coming up on the second time.