I queue for the highest dungeon I'm allowed into on that class, and chain run it as many times as I can stomach. If it's a DPS class, I also fill Hunting Logs while waiting, but at least on Hyperion, lvl 15-49 DPS queues were only ~5 Minutes while leveling my Dragoon a couple weeks ago. Also don't forget to do each Guildhest at least once per class, and do your low level roulette every day, and make sure to be on your lowbie when you get challenge log entries.