I see many new members choose to have one word as their username. Most of the time, it's their first name, or it can be a business name.
The latter is not a good idea, in my opinion, because it doesn't allow us to know you as a person. But that's not the main subject of my article.
I want to focus on choosing your first name as username. Let me explain to you why it's a not good idea. Let's say you choose to call yourself marilyn. No offense to those who might have chosen that username, it came off the top of my head.
So. You are marilyn at APSense. A friend tells me that marilyn wrote a great article, but he doesn't remember the title, and the article was written a few months ago. It then won't appear in the first page of the articles directory. Ok. No problem, I type "marilyn" ( without the quotes ) into the "search for people" tool at the top right of my APSense homepage. I do get positive results. Notice, I said "results". There are a good number of marilyn with last names, AND at least 8 different members who chose "marilyn" as username. Man, will I go through all their profiles to find the article? No way. I will ask for more details to my friend. If he can find it in his notifications, good. But remember, it was written months ago, so chances are, if mny friend is quite active at APSense, the notification for that article will be on page 59. Will he look that hard? Not sure. He will give me details about the article's topic, I will google it and find other sites who talk about it.