Keep headers/logos under 125 pixels high. It takes up valuable viewing space, especially for laptop users, that is best left for the good stuff to appear"above the fold." Take a cue from the big companies, simple logos done well say it all. This is our #1 pet peeve - screaming logos and headers!
The rename your login url to secure your wordpress website Codex has an outline of what permissions are okay. File and directory permissions can be changed either through an FTP client or within the page from your hosting company.
Strong passwords - Do what you can to use a strong password, alpha-numeric. Easy home to remember passwords are easy to guess!
Move your wp-config.php file up one directory from the WordPress root. WordPress will look for it if it can't be found in the root directory. Also, nobody will be able to read the document unless they've SSH or FTP access.
Make a note of your password! I suggest the paid or free version of the protected software *Roboform* to remember your passwords.
But realize that online security is something that you must start thinking about. Don't only be the type that is reactive, take action to begin today protecting yourself. Do not let Joe the Hacker make your life miserable and turn all in creating come crashing down in a matter of seconds, that you've worked hard.