Photoshop

Using Layers

 * 1) To keep your textures as editable as possible, create layer groups for each type of texture map such as Color, Emissive, Bump, etc. A common use for this would be to put the solid colors for the object on one layer and dirt and grime, etc on its own layer in the same group.
 * 2) When each texture group is ready, turn the visibility of the other groups off, and save in a lossless format (psd or tiff).

Creating Maps for Unity Shaders
Unity uses in shaders like Specular, a double map: the RGB channeles controls de Difuse, and the Alpha channel controls the Specular.

Usually the Specular Map is based or similar to the Difusse.

To generate the Specular map:


 * 1) Open the Channel windows
 * 2) Duplicate one of the RGB channels
 * 3) Rename to Alpha 1
 * 4) Edit it (if neccesary)
 * 5) Save in .psd or .png format.