Here lists some must-read articles and things you might want to read along.

• Making Half-Life Mods Part 1 - An article written by one of the creators of Team Fortress, this article explains what it means to make a mod
• Making Half-Life Mods Part 2 - Continuation of the article about mods, this tackles some tips and advise on builing up your modding team and the process of making a mod in five weeks.
• Exploiting the custom game menu - A supplement for Custom Menu Art for your MOD, this shows the basics of using the custom game system of Half-Life (which is implemented in Xash3D).

• TBA