Comments from Ash:
Load the game and allow the opening sequence to complete. Leave the game at the "Push Start" screen and Ash will eventually start to make comments.
When mushrooms appear, collect them, leave the screen, then return to collect them again. Repeat this until they no longer appear.
When you are mixing mushrooms in your inventory, you will hear a sound. When you are wandering around the same sound will indicated that a mushroom has appeared. You can also wait for the sound to play again to get another mushroom. Note: Listen for that sound when fighting the last Boss.
When fighting a Deadite or Hellbilly, turn on your chain saw and slash at them. After a few hits Ash should jam the chainsaw into them and keep it there. Then, use the ax and hit the Deadite while your chain saw is still in them. When they die, they will usually leave behind a Large med-kit. You can also use the other weapons instead of the ax, but it just wastes ammunition.