I'll assume that this is your character, so I'll suggest that you train at yeti cave or goblin land.
to unlock yeti cave, you need to clear yeti plateau in history, Xpecial has a guide on how to do it here -->http://www.mylunia.net/forum/showthread.php?t=10394
yeti cave is a raid stage, you'll need to farm stone embed with a magical property from statues in some of the ep3 stages, stage 3-10 and 3-9 has them I think.
Goblin land is your next alternative, and I mean the Legend one. You'll have to solo that stage for best exp. So, if you cant find a yeti cave party at times like 1am, do this. You just basically go to 1 of the 3 gridded maps, from the beginning, u can go up, right, or down (Make sure you get all the quest in the beginning room first). Just do them all 1 by 1, you have to restart the stage each time you finish one. Collect all drops and do all the quest there for best exp. This is why you have to solo for best exp, so you don't have to fight over drops to complete quests. They are repeatable. Once you did all 3 grids and killed all threee boss, you can turn in the boss quest at the big tree. Then just repeat it. The stage is fairly easy to solo, plus it gives out alot of bravery potion, apple, and mana rejuvenate potions in the stage.
Mai and eternal mentioned that you can farm yeti plateau for fast exp, but I don't think I would suggest that since it seems that you are not familiar with the game yet. If you do that, later on you'll just be called a 'yeti noob' with lack of staging and raiding skills.
To everyone that might want to suggest yeti plateau, please stop, as we really don't want to ruin lunia anymore than it already is, plus, it'll bored new players of this game really really fast. Which will also kill our population.
Please do a fair share of staging in addition to the side stages (staging is the best way to get rare items). Also, at lvl 45+ you can start doing kanhel raids. The way to unlock kanhel is also explained in Xpecials guide that i linked above.