First, ignore the language wars. They are all BS. You want to use PHP, use PHP. Just keep in mind that every language was written for a fairly specific task and it's very good at that task. Don't try to use C to write a server-side script. Likewise, it doesn't make sense to use PHP to write an OS. Try to understand what problem you want to solve and then pick the right tool for the job based on performance, libraries available, community support and past projects that are similar to yours.

Now on to becoming a better programmer:

Find a good project and read some theory books on debugging and how to write code in general (check amazon.com and read the reviews). Books like Code Complete 2nd edition and Beautiful Code. If you want to be more serious about it, the Computer Science series by Knuth will give you all you need to know to get a CS degree, but they are boring so you have to be willing to stick with them. Those books, 3 volumes, are the bibles of Computer Science ( yes, someone will disagree) and as such they are theory. However, you need to know a good deal of that theory to write good software. Specifically, you can concentrate on searching/sorting algorithms, algorithm analyses and machine architecture.

In general, you will find that there is a HUGE learning curve to understand what the computer is doing with your program and how to write code that makes sense, which makes you a good developer. However, the time you invest in learning what happens behind the scenes is worth it's weight in gold, independent of the language you use.

Always try to figure out what the tool/language you are using is trying to do and don't blindly trust it.

Never, ever skimp on comments. You don't have to write a novel and explain that you are adding 2 to variable i, but do explain what the function is doing or what a complex bit of code is doing, this will save you hours when trying to find that bug.

Use a version control tool. The simplest one to use would be Subversion and the book for it is free online. There are also free Subversion hosting services such as http://beanstalkapp.com/.

Depending on how serious you are, you might want to look at the coursework from colleges like Stanford. Many top schools post their coursework with lectures online.

Google is your best friend. Just paste the compiler error and remove any variable names and you will often find people who had the same exact problem with possible solutions. You might have to play with the search string, but you will often arrive at an answer quite fast in this manner.

Try to find mentors on forums and newsgroups. This will take time as you develop relationships with people, but it's the best way to learn as the software development industry is still, very much, based on the notion of apprenticeship.

Try to study some open source projects. Little ones are best, as they are least complicated usually. Trying to figure out what someone else wrote will make you a better programmer in a hurry, because you will notice mistakes people make and how you would like to do things differently.

Lastly, think about which tool/program/etc. that you would love to have or rewrite an existing project in your own style and do it. The first one will be horrible, full of bugs and many many problems, but it will teach you more than most classes you take in school.