How to create textures with Paint .NET and notepad.
how to extract a texture from the game, and then edit it.
how to make those User Bars often seen on Forums.
This tutorial will show you how to create custom textures for use in creating maps for the Source engine
From bump mapping to phong shading - This tutorial covers a large number of texture effects. Look inside to discover how to give your textures an extra special touch.
This tutorial is a small introduction to skins.
This tutorial walks you through creating a material with transparency and then placing it into VGUI menu.
This covers creation of custom textures in the Source engine
how to make a signature for a forum, using pixel stretch technique to give a blurred matching background.
Surface Materials for Source
How to create an alpha blending texture.
How to painlessly make functional blend textures.
Our first tutorial is creating a static spray with no transparency.
This is the first of a series of texturing tutorials from Gronblad, and covers making a texture, and converting it for use in Hammer and HalfLife 2
Pixelated Sprite Sprays
How to make a transparent texture.
What are source spraylogos? Spraylogos are images you can place on most surfaces in source multiplayer games with the exception of models.
This shows you how to make a blend texture for use on displacements and was created by Stadric.
Creating Animated Sprays
Learn how to use custom textures in HL2 and CS:S.
This tutorial fom Stadric shows how to make textures look more realistic with depth and texture, by specular bumpmapping.
how to make an animated texture work for you in Half-Life. You will need these programs: Photoshop and VTFEdit
Custom particles in maps & spritesheet VTFs
Creating a Fading Spray
This tutorial will cover the basics of reskinning a model for Hammer and HalfLife2.
a pretty simple tutorial on making transparent textures
Visible representation of water textures
Tutorial on making a spray decal that contains a full range of transparency, such as text or graffiti like used in HL2.
Our second tutorial is creating a static spray with transparency.
Using GIMP to make self illuminating textures
If I can find a photograph of something similar, it's fairly straightforward to turn it into a texture file.