Selecting what your Categories are called should be a thought out process and not just thrown together. I learned by watching my site ranking through Google Webmaster tools, that putting some thought behind what you have listed can be very beneficial. I am going to use my WA Promotion site as an example going forward here.
What Tipped Me Off
So one day I was checking out my stats and found that I had a good ranking on the search phrase: Wealthy Affiliate Success Stories
At first I was not sure as to why I was even ranking with this term as I had never used Success Stories as part of any of my targeted keywords. So I hopped over to an incognito browsing session and did a Google search on the phrase to see just how I was getting ranked. Low and behold, there I was right where Google predicted I would be. So I decided to click on the link and see if I could figure out where it was picking out the keywords. When it took me to my home page I realized that it was grabbing Wealthy and Affiliate out of my URL and then it was grabbing Success Stories out of my Category list that I had in my widget area.The Experiment
Now that I had an idea of what was going on I did a little keyword research based off of using Wealthy Affiliate and looked for something that would make sense as a category. That is when I found that having the year "2014" along with Wealthy Affiliate would be a beneficial keyword set. So I added a category: Year - 2014.
As you can see, I am now climbing the ranks with the keyword phrase, "Wealthy Affiliate 2014."