Item bitmaps should be 64x32 with the first tile the item itself and the second tile with a possible animation. The animation isn't necessary. Items include Treasure Chests, potions, and the like. I probably won't have weapons on screen, so making those will be pointless.

I could also use small things, such as doors, pits, and other obstacles. Those would also be the same as item tilesets, but, obviously, won't be used for items but complex, user programmable objects.