First off, change your password if it is something simple to remember. Make it difficult with lower and upper case characters, and numbers, etc. Make sure and write it down. Also, make sure that your email password is not something that is easy to guess.
Secondly, do not have any other admins on your blog except for you.
Thirdly, if someone were to gain access to your blog, they cannot delete you as an admin if you are the person who set up the blog. WordPress made a change a little while ago and no they would have to request that you be removed by contacting staff and staff would have to have your permission before they would delete you from the blog.