On the SitePoint Web Blog there's a recent post by George Fekete with a few suggestions about how to be a good developer, regardless of the language or technology you're using.
As a PHP developer, or any kind of developer as a matter of fact, you need to constantly improve yourself in this ever-changing industry; you need to learn and use new knowledge every day. What successful developers have in common, is that they care about programming a lot, they are professionals treating good programming practices as a form of art. In this article, you’ll learn about how to be a better developer by following the “etiquette” of programming and you’ll learn how to use this information to perhaps teach others to better themselves.
He starts with some tips about "being professional" overall that include things like being responsible and having a strong work ethic. Then he moves into writing good code. This isn't about actual code examples, more about good practices and tools. He also shares some tips about how to keep things (and yourself) on track and tips on how to "be a master" when it comes to social interactions and the work you're doing.