Stock up on Spyglasses

Items are incredibly useful in Shin Megami Tensei V. They essentially give any human characters access to on-demand healing and a full array of elemental attacks, which can easily turn the tides in battle when you’re in a pinch. While you’ll want to keep at least a few of each item on hand, prioritize grabbing Spyglasses as soon as you access the Cadaver’s Hollow shop.
Spyglasses are your “Scan” spell. They instantly reveal an enemy’s weaknesses and their moveset, which is invaluable in boss battles. While you can ascertain this information via trial and error, you’ll typically waste turns in battle while running the risk that the enemy might block or reflect your attacks. Spyglasses are so cheap that you don’t have much of an excuse not to use them.