-Log in at least two characters (minimum of level 5-1) and have the two characters meet in the same area. Have one character send a duel request and the other character accept it. When the battle begins, have one of the characters run or quit from the battle. The other character will win and earn experience. Do this every hour and your character will level easily.
-You can fight some of the NPCs to level up, then go to the NPC and click "Challenge". Note: Some of them cannot be fought. Note: Do not fight people that are too high of a level because they can still fight back.