One way to gain levels at a descent level is Novice Guide.  
This is an alternative to questing and is more of a grind method.

[Place] Sun City  Near the State Consultant
[NPC] Novice Guide

[Directions]
1) Talk to the Novice Guide
3) Get the quest to kill a mob your level.
4) [Optional] Talk to the Event Official for double exp hour
5) Ride your horse to the 8 Arm Pass to the North
6) Find your assigned mob and finish your quest
7) Return to Novice Guide and turn in the quest

[Notes] The quests can be done repeatedly and so far I haven't found a limit on how many time a day it can be run.  At lvl 34 on double exp time, I get about 500 per kill on bats in 8 arm pass and 10k per Novice Guide quest.  The double exp does not affect the exp reward from Novice Guide as far as I can tell.  The Novice Guide works for levels less than 40 as far as I understand.  With a team, the quest goes very fast and you find a good chunk of your time is spent traveling instead of killing the mobs.
The cons here is no money drops, high pots consumption and hard hits to your horse.

[Lower than 20 Quests]
1) Ability Demonstration ~ 20 Flightless Dragons lvl 13 (Located South of LouCity Gates)
2) Start Your Adventure ~ 20 Condors lvl 16 (Located North of LouCity Gates)
3) The Path to Success ~ 20 Kongwei lvl 16 (Located North of LouCity Gates)

Here is a picture of me getting 10,900 for finishing killing 20 bats.  I would say at my level it is about 5-6, Novice runs for a phases level (ie mind, body etc).