You’ve read a lot of PHP best practises articles and topics all over the internet and try your best at following them during your development. How about the worst practises in PHP development? There’s a nice article on the PHPDev Blog which tells you about a few practises (which I’m sure most of us haven fallen a prey to during our careers) which should be avoided at all costs.
Some of the practices include in the article are “I don’t need no documentation” syndrome and “My code is the way to go” when other better alternates are out there. Why don’t you head out and read the full article there?