Ys VIII: Lacrimosa of DANA

• There aren't a lot of missable items in the game world itself, but there are some missable things locked behind quests, which do have time limits a la some other Falcom games (Trails, for example). You're sent back to the quest board pretty often so if you get in the habit of checking it when you're back and doing quests when they're available you shouldn't miss any.

• Once fishing unlocks get in the habit of checking out bodies of water for fish. There's a character who takes fish and gives you items in return in the village; I didn't notice them until mid-game but they show up early.

• Also, certain characters are better at fishing than others, in a mostly-obvious way, so if you're having trouble with rare fish swap your characters around.

• When you finish raids check with Dogi, he'll usually give you an item.

• There are three 'elements' that characters can have, and for general exploring it's a good idea to have one of each. Bosses, however, generally don't have elemental weaknesses, and you get a 1.1x damage boost for having more than one of the same damage type in your party, so if you think you're about to fight a boss go ahead and swap in two of the same element if you have them. (Bosses are generally pretty well telegraphed.)