Link's quiver can hold up to 20 more arrows by getting the following quivers. Note that the order you play the minigames in does not actually matter as to which quiver you receive.

Upgrade	How to unlock
Large Quiver (holds 40 arrows)	Get a score of 40 or more at the Town Shooting Gallery.
Largest Quiver (holds 50 arrows)	Get a perfect score at the Swamp Shooting Gallery.