There is a lot of information about how you can keep your WordPress blog secure and safe from hackers. Such tips involve keeping your WordPress veresion and plugins updated, as well as backing up all your blog files and database.
From a slightly different perspective, you may also want to take steps to ensure you protect your WordPress login to ensure any unauthorized visitor can gain access to your entire blog. There are several things you can do to help keep the login secure, all that I have done on my blog as well.