This article is part of the Protecting WordPress index, but can be generally applied to your account and security practices!
- Rename the admin user to something unique, but know that your username is published in a variety of locations on your website.
Just renaming the admin user may not necessarily protect your account. - Make sure that each admin user on your account has a secure and unique password.
- Yubikey is an additional option that can further secure your login, check out the details for that here: http://www.yubico.com/