New PHP project, how to best architect it

Question

I have already done a PHP project, and I did a number of things pretty wrong :)

I just had all pages as scripts with php mixed in with html. I also wasn't using a framework like cakephp. And I didn't really use objects, nor had any sort of test suite. :)

This time around I want to get it right. What should I do in terms of good practice approaches? And what am I ok not using? Any suggestions? Tips?