How to properly use a username?

[Gamer_M]

To make a username is easy. First think of a username that you like and original (For example Gamer_M for me) Then you can just use it all the time. This is easier because you don't have to remember every username from every website. Then if your username name is taken. Try adding/removing/changing some of the wording. (For example, Gamer_M to GamerM to Gamer__M to Gamer___M) Then your done.