Killing monsters and doing quests will give you experience points. When you have gained enough experience points you can level up to the next level. The amount of experience required to level up increases as you gain levels, so you will have to kill tougher monsters or do harder quests.
When you level up, you get the choice of how you want to improve the character. Currently, you can choose from the following attributes to increase:
Increase health by +5 HP Increase attack chance by 5 % Increase attack damage by 1 Increase dodge chance by 3 % Choose wisely. Your choice will determine your proficiency at fighting tougher monsters.