Accessing all the Quests.
When you reach level 20 you can choose what type of quests are visible for you, especially because by default there are only a limited amount open. If you press the O button, the quest tab will pop up with a large amount of useful information, such as the black spirit quests, which can reward you with an inventory expansion.
The most important bit about seeing all the quests is at the bottom of the screen. At the bottom there are six small tabs that you can press which will open up access to those quests for you to accept from NPC's.
Take special note of the quests at the top called "Inventory Expansion". These quests reward you with an inventory expansion which is really useful as you normally need to buy these expansions with loyalty points or pearls.
Breath, Strength, and Health
There are three stats in the game that you can level. These are Breath, Strength, and Health.
Breath increases your stamina. To level breath you need to run around. Leveling breath is based on distance, so running in one spot will not help. What you can do is set a path to the next town, click auto-loop, and then press T. This will make your character run back and forth which will increase your endurance.
Strength increases the amount of weight you can carry. To increase strength you need to buy a trade pack from a trader and walk around with that in the same way as you would do when you are training your endurance. So pick a destination on the map, press auto-loop, and then press T to auto-walk.
Health increases your total HP. The only way to level health is to eat food, so be sure to always have a snack on you.