If you want to add category and client templates to the WordPress plugin Simple Portfolio (by Patrick Brouwer) make sure you use the custom Taxonomies created by the plugin.

To find the two taxonomies that you’ll need go to the plugin’s folder and open simple-portfolio.php and search for “taxonomy”. You’ll fine the two that you’ll need:

• portfolio-clients
• portfolio-categories

In order to get my new template files to work in my theme I named my files this:

• taxonomy-portfolio-categories.php
• taxonomy-portfolio-clients.php

Hope this helps.