Copy-pasted from the [url=http://maplestory.nexon.net/News/News.aspx?boardNo=103&contentNo=00CS3&pageIndex=1]Update Notes[/url].
* Ambition: Increase it by hunting boss monsters. Effect: Increases your Attack for Battle Mode (coming soon).
* Empathy: Increase it by harvesting herbs. Effect: Increases your Max MP and your Quest EXP.
* Insight: Increase it by mining. Effect: Increases your Accuracy and Avoidability and allows you to check the Hidden Potential of items without using a Magnifying Glass.
* Willpower: Increase it by participating in party quests. Effect: Increases Weapon Defense and Magic Defense, and builds resistance to abnormal status effects.
* Diligence: Increase it by crafting. Effect: Increases scroll success rates and doubles profession mastery gain.
* Charm: Increase it by gaining fame, equipping Cash equipment, changing your hair or face style, or changing your hair, eye, or skin color. Effect: Gives quests to add a Pocket slot to your Equip Inventory, to gain special items, and to gain Facial Expression Cash Item. You can purchase Pocket Items from Nave in Henesys Market.
* Raising your level in a trait will eventually unlock quests that will reward you with medals specific to that trait.
Edit: Certain party quests also raise traits like Empathy and Insight, for some reason. And Willpower also increases if you stay online for a certain amount of time.