Enhancing your items and weapons to make them more effective. Focus on your top tier, multiple star, items because they will usually be in use for a longer period of time. Check a weapon's maximum level before leveling it up to avoid wasting resources on an item that is already close to its limit. Your inventory space is limited. Upgrade it often to have room for the weapons and equipment that are given as rewards when a level is completed. Make sure to keep your inventory in good shape by expending extra weapons and other items to upgrade your best equipment.