A good resource for "best practises" for web development?

I’m currently working on my first big project where I am doing everything myself:

HTML
CSS
PHP
MySQL

I started out by building a skeleton website that was fully functional, with everything appearing in simple black and white text, occasionally grouped together in <fieldsets>.

I then built a few template HTML + CSS pages, and am currently going through the process of what is proving to be the tedious and laborious task of transferring every page in to a template, and making it look good. I am convinced there is a simpler, easier way of doing this.

I’ve never done this stuff “out there in the field” hence I have never really been exposed to “best practises”. I have learnt all of my PHP out of books, and I’ve never used a framework.

Can anyone recommend a good resource (either online, or a book I can buy) that contains best practises for this sort of stuff, as well as clear explanations as to [B][I]why things should done a certain way[/I][/B]?

Thanks.

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