Securing php from rogue php scripts

Hi there I have been reading about certain php scripts that, if used incorrectly, can compromise servers. There are certain open source scripts that I know if (no names mentioned) that have exploits that allow this and I want to know if there is a "How to" or best practice anywhere for securing PHP against this. I was told to add some stuff to the php.ini file to prevent certain actions (phpinfo ,system, include, chown, chmod, exec, passthru, mail, readfile , dir , read, readdir) but was wondering if someone could give some advice Thanks Ade