Press [F10] to enable cheat mode. Then press one of the following keys to activate the corresponding cheat function.
[Backspace] - Reduce extra life requirements to 5
[=] - Rapid fire
Go to the Crypt in Mileth. When there, go to the second floor and kill spiders. The spiders drop "Spider's Eye", which can be sold to the Dark Wizard in Mileth for 500 gp each. This is a good way to make money, especially for beginners.
Faster move or attack
Press [F9], then add yourself to your ignore list. You can attack and move without a delay because the attack animation will not happen.