Never Use the Default WordPress Admin Username
When installing WordPress, the default username into the WordPress admin is “admin”. You should always change it to something else. In WordPress 3.0, the installation process gives you a chance to rename it then. Take the opportunity to rename it during the installation process. Because once you set it, then you can not rename it later. Unless you install and use the Admin Renamer plugin.
If you had installed WordPress via an earlier version that did not allow you to set the admin username, then use the Admin renamer plugin to change it.
The reason you don’t want to use “admin” as the username is because that is the username that hackers will use as their first attempt when trying to brute force guess your access. If you use an obscure “username”, then they have to guess both your username and password correctly as opposed to just your username.
Another security tip is to not generate the WordPress meta generator tag.
Learn more about WordPress security here.