Honestly if you are starting out on your own and you don't have to fit in with a team of existing PHP developers then go with Python or Ruby (or perhaps Groovy if you like the JVM) instead.
PHP is not a language that I would recommend to anyone who already knows how to program. With Ruby you've got Rails for big heavy projects, Padrino and Sinatra for lighter weight stuff, and with Python you have Django and Pyramid when you need "batteries included" web frameworks and Flask and Bottle when you need something lightweight. Groovy has Grails (like Rails but for Groovy) and Ratpack for the more lightweight approach.
Don't misunderstand I've had PHP jobs on and off for the last 16 years and it has been good to me, but once I started working in languages like Python and Ruby as well I started to realise the downsides of PHP.
Also, if you are going to do freelance webdev you are going to need to focus some of your attention on JavaScript; some things need to be scripted in the UI. That and you will need to look at CSS, specifically CSS 3, and HTML, specifically HTML5 these days, but XHTML 4 as well.
Good luck - if you steer clear of PHP you will have a much happier time...