Be a Pro of PHP: keep working with PHP and Symfony, try to run it on Facebook HHVM 🐘!

Learn JS Frameworks: like Google AngularJS or Facebook React.

Try other Linux distributions: like the simple, lightweight distribution ArchLinux which Keep It Simple.

Practice your logic: do online challenges, to earn point on HackerRank and Code in Game!

Be a Git Ninja: take the time to read the whole Git Pro Book if you don't feel confortable with Git.

Learn other languages: like the C to understand memory management and strong explicit typing or Haskell to discover the magical world of pure functionnal programming!

Studing Algorithms: if you don't be afraid by a bit of maths, I advice you to read the really great book of Jeff Erickson of Illinois University.