When I started blogging, someone showed me how to enter my blogs into WordPress. They walked me through how to enter content, pictures, select categories and add tags. With that, I was off and running.
I published post after post, until one day, I stopped and looked at all of the tags on our site. I realized that we certainly had a lot of them (and even a couple of extra categories that weren't used much). So, I did a little research and found that I hadn't quite understood the business of categories and tags when I started (I speak only for myself and not our other contributors). Here's what I found.

Category vs. Tag?

The first question you should ask yourself, is it a category or a tag? A category is a general way to classify your posts – kind of like your Table of Contents. If you only have one or two posts that fit into a category, it may be more appropriate to select a tag. Tags are more specific. They are keywords that help people find other more specific related information – like your Index. For example, if you are a retailer who sells apparel, you may have categories on Women’s, Men’s and Children’s Fashions. Your tags might include Denim, Jackets, and so forth. While you can have categories and tags that are the same, there's not much point to it - so pick one or the other.

Tag with Purpose

So here’s where it got tricky for me. You have to use your tags in a way that is useful. It sounds easy enough, but when I started, I was probably a little tag crazy; adding tags for anything that I thought might be searchable. As an example, I tagged the name of a motivational speaker at a convention who has nothing to do with our industry, but is well known in her own field. Since the purpose of tagging articles is to help your audience find similar articles within your blog, it served me no purpose to have a tag for that speaker who we will likely never reference again. Since this was a motivational speaker, I made sure there was a tag "motivation" knowing that we are likely to have more motivational pieces. Lesson learned – make your tags purposeful.

To Capitalize or Not?

Another thing that threw me was whether or not tags are case sensitive. The research on this was a little confusing because in some cases, tags are case sensitive (depending on what program you’re using or how you’re entering your tags). But if you’re blogging in WordPress, according to their Frequently Asked Questions, their tags are NOT case sensitive. Therefore "Tags" is the same as "tags". I think the key here is to keep some level of consistency. Use the same thought for tagging in singular or plurals – stay consistent (but don't use both - ie. tag and tags).

Eliminate Redundancy

In order to prevent creating redundant tags, try to work from the tags you already have created. If you’re blogging in WordPress, you can pick from the most used tags. For example, if you write a post and tag it "Spring Fashions 2013" and write another post tagged "2013 Spring Fashions," you may have similar posts that belong in one category. You wind up diluting your tags and people won't know which to pick. Additionally, the posts will only show up in the tag with the exact match. Of course, if you need to add new ones, go for it. But do make sure they are relevant to your site.

Tag Cleanup

If you’re just starting to blog, you can start the tagging process right. But, if you’re like me and have already started, you have to go back and clean up your tags. This means going back and deleting or changing redundant or useless tags. Then you’ll need to go through every post and make sure they are tagged properly.
Once you understand tags and categories, and everything is working as it should, your visitors will be able to easily navigate your blog – ensuring that they’ll return to your site again and again.