You'll start encountering slightly faster enemies and some ranged attackers. This is where your dodging skills become more important. Continue to prioritize experience. In the shop, start looking for your first defensive items like Bandana (+HP) or Plastic Armor (+Armor). If you're struggling with damage, consider an item that boosts your Attack Speed or Damage. By Wave 5, you should have at least two decent weapons and a few stat upgrades under your belt. Don't be afraid to kite enemies around the arena.
