I am a frequent contributor to the forums at The Cartographers' Guild. In the course of my time there, I have written several tutorials and guides. Here is a complete list:
Creating a local-scale tree texture in Photoshop
This tutorial was adapted from a technique at the Cartotalk forums, but the original was very difficult to understand. I clarified it and provided illustrations.
An Introduction to Image Export Formats
Many beginning artists have never learned the differences between the various image formats available to them and sometimes pick a final filetype that is suboptimal in terms of compression ratio or visual quality. Here, I have attempted to provide information about all of the common formats and when to use each one.
Using Channels to Separate an Object from its Background in Photoshop
I see a lot of inexperienced artists try to cut an object off of its background by painting a mask, using the pen tool, or even the eraser! This is a much easier method that aims to preserve the detail of the subject's edges. Also, since it does not rely on hand-painting, it can be used on video footage. It is, in fact, the basis behind the process of chroma keying.
Using Photoshop's Clone Stamp tool for better brush work
Many cartographers use brushes to put down mountains and trees, but anywhere the brush strokes overlap, the "white" parts are revealed to be transparent. The Clone Stamp tool, while not as elegant as the Brush tool, can be used to counteract this behavior.
Essential River Guidelines for Mapping
The Cartographers' Guild has a small cadre of self-styled "River Police" who examine maps for unrealistic water behavior. This guide collects their wisdom into a single place and cross-indexes other river-related discussions.
Create an isometric medieval tower icon in Illustrator
A simple Illustrator exercise that demonstrates how to make small icons for fantasy maps.