One of the website developers at Eggplant Digital suggested a few tips on how to make your WordPress install harder:
In order of importance:
1. Keep your WordPress install up to date.
2. NEVER leaving the generic username ‘admin’ as your primary WordPress username, doing so makes it too easy to crack your WordPress admin password.
3. Create an admin username password which are less memorable, but more secure than your current ones. For example, instead of using something like your last name and date of birth, use a randomly generated password with numbers and letters and write it down somewhere that you can access it quickly. Great site for random passwords is: http://www.grc.com/passwords.htm
4. Keep your WordPress plugins up to date and don’t use plugins which are being maintained by the developer.
5. Install the Login Lockdown plugin that limits failed login attempts and reports any suspicious logins to you and/or limit the number of IPs users can login from.
6. Check at http://sameip.org how many sites are hosted via your IP address. If there are too many, then ask your host for a dedicated IP address.