Eudemons Online is used to upgrade for a newbie, which is normal behavior. I personally started at K I will use the name of area from that region. Substitute with the equivalent for your region if you do not feel like changing areas. Obviously specific quests will be different.
That is still a superior source of exp at this point. Though yes they will give you an annoying number of kill this boss quests. You do not worry about those do what you can.You also can buy some Eudemons Online Gold.
After the level 20 mark a big scary place called Prairie cave opens up to you, but you do not want to go there yet. Instead head over to sprites Forest and do some quests out here. This is also where you will find the first repeatable quests that are really worth doing.
The repeatable quest for leopard skins is worth doing a couple times until you get the quest for treat roots, which also provides mount flutes. Abuse this quest. The old man who gives you the quest is directly next to leafy treats, meaning you can cut them to pieces and have a very short travel time between collecting and turning in. At 25 you will want to move up to Belmar Plateau. If you did like I told you and got a 2hand weapon this should not take too long Leafy.
Both areas have repeatable quests which as this point you should have figured out the best way to go about doing.
Grinding the repeatable has the added bonus of paying out a good chunk of change at this point too so you will find yourself with a few Eudemons Points by the time you reach your level 30 job change.