1.Try to use SSH instead of FTP connection to your server.If someone has got your FTP information,he can do anything with your site,add unwanted item,scam your site and use it for his purpose even though you are not aware of it.But,in SSH ,all are encrypted during the transfer of the files and hence connection is much more secure than the latter one.

2.add

code]
if(preg_match(’#’ . basename(__FILE__) . ‘#’, $_SERVER[’PHP_SELF’])){
header($_SERVER[’HTTP_HOST’]);
exit();
}
[/code]

to the top of any plugins for additional security.

3.Always create a strong password for security,or else it will be open to hackers on internet  to explore them easily.

4.update your plugins and wordpress whenever update is found since older versions can have security leaks which are been removed in newer ones.

5.have you ever noticed that some of the wordpress files have been indexed by google,which is very much dangerous?..Yes it is possible..so disallow all these files to be indexed by google,which can be done by adding in robots.txt file at root of site.