Where To Start?

I have some experience playing the guitar. I am mostly self taught and took lessons for a short time. I am having difficulty figuring out what I should learn next to better my playing.

I can play all my major and minor chords and know how to play the C scale (in different positions). I have been mostly learning how to play songs I like (that aren't too difficult) using guitar pro and power tab. What lesson should I start off on and move on to afterwards?