Give your categories and posts their own individual templates.
Easily apply templates to your category archive pages and posts with this plugin.
Valid templates are files placed your theme folder with the following code at the beginning of them:
For Post Templates: Template Name: Blog Template
For Archive Templates: Archive Template: Blog Template
Through this plugin's options panel, you can choose which templates are applied to categories and posts. Even choose their priority over one another. You can even apply a template to an individual post. Please report any bugs you come across.