There's two stages to making a texture. A program such as UV Mapper helps with the first stage -- getting a template to show you which part of the texturemap covers which part of a model. That's fairly simple. The complexities of these programs mostly hit when you're setting up the UV mapping for a model. Most of the work needs to be done in a paint program, such as Photoshop or The GIMP. I've found the most useful feature to be layers. Put the template on one layer, draw the final texture on other layers.