Gain Experience

Players who hit a monster will be able to see its health bar.

The player or player's party will gain the experience points from a monster if he/she deals the final death blow, however, if the first attacker did 40% damage, then he/she becomes the killer.

The killer will also exclusively see the monster's drops for several seconds, and his/her party. After this, everyone else can also see the drops and pick them up.
 

As you can see, it is best to EXP in a map where the monster levels are near your level.
If those maps are too hard for you to solo, you can party up with others. If you're in a party, the party level (average character level of all party members) is used instead of your character's level in the above table.

The level-based EXP modifier table listed above is also applied on Party Quests (using average character level of each party member) and most repeatable Quests.