1) Save your game when you are sure that you have enough of ammo to continue. The game was designed in a way that you can collect almost twice as much ammo as you would need. Beginners tend to get excited and spend a way too much of ammo. They may end up without ammo or money to buy additional ammo.
2) Some lift cars are tricky. They won't stop where you expect them to stop. You should alwaus listen to the stop sound. 
3) Read the scrolls. Most of them contain important information. 
4) Color of the key corresponds to the color of the lock.
  
Master key will open any lock. 
Some rooms were designed to kill ! It means that you have only one chance to make a right move. If you fail then sorry... press A to abort.
