I would start on the front end and
I would start with looking into Bootstrap and jquery. And look at using PHP to deliver the webservice data to jquery.
I would also google some MVC PHP tutorals to get some idea of how MVC works since alot of modern frameworks are modeled after it.
here's some tutorials(middle of the page) on using angularjs with php: http://www.angularcode.com/
now your ready to swap out php for another server technology. nodejs, RoR, whatever.
Once you have that in your pocket you'll be ready to try any of the new js frameworks that are being mentioned here.