I believe that a blog should have a very limited number of categories. Depending on your topic and how broad you go in depth with your primary topic will determine how many categories you need, if you even need any. After two years of blogging, I have learned a lot about categorizing and organizing your blog content.
The trick is in making your blog very user friendly. Many people believe that there are tricks in making your blog more search engine friendly; however, the best trick is to understand that search engines want exactly what readers want. Your blog needs to be very friendly for users. When you are considering the number of categories to use, also consider what would make the reader’s experience better.
Using Categories On A Blog
To me, I feel like a blog should have around 5 to 7 categories. You can have a little less and a little more depending on your topic. But typically the sweet spot is in having around 5 to 7 primary categories. Choosing your categories is very important. I would suggest looking at http://dir.yahoo.com and http://dmoz.org to see how they did their categories for the same topic you blog about. Also, I would suggest that you assign only one category per post.
What About Tagging
Tagging is a very important system. You should use around 3 to 5 tags per post. This enables users to search and find your content using two systems. Users have the option of searching by primary category as well as a second option of searching content based of primary keywords you have assigned it. If you assign each post around 3 to 5 keyword phrases, TAGS, then this will really help users find the information that they are looking for.
Where Do I Display My Categories and Tags
The sidebar is a perfect place to display your categories and tags. Typically I display them very high up on the sidebar above the top fold. Usually I am pretty standardized and display my Page Menu first - home, about, contact, etc.. - and then I display my category links next and then below categories I will then display my tag section. If you’re using WordPress, setting this up is very simple. WordPress includes a system called Sidebar Widgets which includes the ability to drag and drop these sections into place.
