The trick is to level 2 or more jobs right from start lol
I had 2 50s 1 49 in 2.0 before finishing the story and now 2 60s and 1 59 before finishing Hevanesward story. The trick is to have friends to level along or to have someone or something to wait for so you have loaaaaads time to fill lol.

But seriously I tend to level with
- Duty Roulettes (mostly leveling, guildhest, trials)
- Challenge Log (FATE challenges, giving commendations, running roulettes)
- FATEs occasionally to finish a level or to fill some DF waittime only (the real grind would cost my mind)
- Run current dungeon 1-3 times for gear upgrades and to test new skills
- Till level 42 or so hunting log is also worth to be done

Currently I do my dark knight casually (if you can call it that way) and make about 1/4 to 1/2 level in 50+ per day.

And I really mean it find someone that levels a job with you even if he/she is like 5 level difference to you the company and fun is definitely worth it ^^