WP blog hacked - advice on chmod

One of my wordpress blog hacked, which hosting in a offshore server.
i got a mail from host which is given below.

First of all sorry for inconvenience caused, in last 2 days.

PROBLEM : Some of the sites using wordpress, drupal, typo or other 3 part scripts has some files or folders that has full permissions. Hacker can easily hack these sites.

Solutions :

- change your cpanel & FTP password (should be combination of words, numbers & special characters.).

- check your & your clients public_html folders, and remove files which are not uploaded by you or your clients.

- IMP - check files & folders permissions it should not be full writable (777 or rwxrwxrwx).
http://www.elated.com/articles/understanding-permissions/

- upgrade all their 3rd party PHP scripts to the latest stable/secure versions.

FTP connection will start working in next 1-2 hours.
Thanks for your kind cooperation.

How can i avoid this?
i have confusion with chmod in wp blog?

can anyone advice me suitable chmod for wp blog files ?

 

Had you installed any third-party theme? Some of hacked themes have backdoor.

 

yes, i have installed some themes downloaded from net.
which one is reliable theme site?