Make sure to check your challenge log and do the bits (leves/fates/roulettes/hests) that get you bonus experience.

When doing the hests, the experience for a hest you've already completed it pretty minimal. If you're looking for a fast way to get the challenge log experience, spam the low level hests to get the log bonus.

If you're not a tank or heals, try to partner with someone else who's leveling one for faster queues.