The following guides were written by me or include me as a contributor (they are organized by date, from oldest to newest written):
How to Unlock the Single-Player Bonus Modes (aka Cheat Options)
How to Add Custom Maps to AVP Classic 2000
How to Play the Single-Player Levels Cooperatively
How to Make Custom Skins, Sounds, and FMVs
How to Make a Custom Menu Background
Olde's Guide on the Alien
Debug Mode (Contributor)
How to Spawn Any Bots in Any Level
Making Sense of the Predator's Health and Energy
Olde's Guide on the Marine
How to Enable Unlimited Saves + How to Quick Save and Quick Load
Fun Things You Can Do in AVP Multiplayer
Olde's Guide on the Predator
How To Get AVP Gold Edition To Work Flawlessly On Modern Operating Systems
Community's Guide to New Players (Contributor)
Level-Creation Guide (Contributor)
Weapons and Ammo Charts
Multiplayer Map Guide
uMod Guide
Single-Player Walkthrough
Wall-Clipping Guide
Modding Tools and General Resources
How to Auto-Skip the Launcher and Logos
The following AvP guides were not written by me:
Playing Single-Player levels as different species (By MandatoryAlcatraz)
In-Depth Marine Weapons Guide (By MandatoryAlcatraz)
A Predator's weapon guide (By Ernix)