(Yes, you found the hidden hint page!)
First and foremost, if you are new to Doom, don't play on a high difficulty level. The high difficulty setting is designed to present a challenge to seasoned players. Even I, the designer, can't finish the level at the highest setting (I'm not very good at playing Doom however). There are almost as many ladies at the lower settings (though they tend to have a lesser number of 'Vicki's', which are really tough) but you have significantly more ammo, armor and health at the lower levels.
Many cheat codes are usable at the keyboard for things like becoming invulnerable and getting all the weapons and ammo. (This is really cheating though.)
There is a hidden 'super weapon' inside the strip club that you can get without cheat codes.
There is another real nice weapon hidden outside the strip club.
How do you get a ticket to get in the stip bar?
How do you use the ticket?
Where is the employees key?
Where is that managers key?
How do you get behind the bar?
Getting to level two may not be obvious.
The trick to wallowing in level two gore.