Angel Slime Hat

The Angel Slime Hat gives a tiny amount of defense, and more importantly triples the amount of experience you get up to level 59! Obtaining it should be one of your top priorities when starting out. To get the hat, you need to find an NPC wearing it. There should be one in every starter town; the one in the image to the right is the NPC in the elf starting town. Talk to this NPC and select the first option (はい) and she'll give you the hat.

To equip the hat, open your menu (Default hotkey: V), select the third option on the left, and select the hat slot, then find the hat and equip it. Enjoy your tripled experience gain!