FREE image editing tools and tutorials.
The GIMP (GNU Image Manipulation Program). Praise
The GIMP is a free (open source) image/photo editor for virtually all platforms. Tutorials and plugins are available at the site.
Inkscape Praise
Inkscape is a free vector based drawing program available for most operating systems. It's especially good for drawing high quality decals and prints.
Paint.NET
Paint.NET is a free image/photo editor for Windows platforms. Tutorials and plugins are available at the site.