For your website and page content to rank above all others, you have to demonstrate popularity and authority on Google. You have to convince Google that people value and appreciate your content.
Avoid SEO frustration. FInd out what you need to know up-front so you can your align expectations with what's most likely going to happen as your site gets optimized.
This post talks about how to pick categories and tags for your blog and contains recommendations / best practices for their implementation and use.