Nerve Gas Vial, Stamina Booster / Muscle Booster are good items for surviving human attacks (especially in the last two stages).
Tear Gas Vial is extremely useful as using it (along with damage buffing items noted below) gives you the possibility of killing a few enemies in one turn, minimizing the damage you take later.
DumDum Bullets / Grindstone are good for additional damage.
A character (or 2) with a Healing Adrenaline Rush IS A MUST, especially for later Story Missions or Roadmap Missions.
Healing items (Replenish, First Aid Kit, Energy Burst, High Replenish, First Aid Case, Deluxe Replenish) ARE A MUST, especially for later Story Missions or Roadmap Missions.
Good kit: Nerve Gas Vial, Tear Gas Vial, Replenish*, Smelling Salts.
Replenish can be replaced by High Replenish in harder missions.