I have been playing guitar for 4 years and I always felt that I learned so much from lessons that I didn't feel the need to quit. The time has come. I am going to be turning 16 soon which means I will need more time for a job and such and I feel that I will stop by every once and awhile to see my teacher, but will probably never get another lesson. What is something that I can learn in these last few months that will really help me? I already know about keys, modes, soloing, etc. all that stuff. But what is something kind of advance that I should probably learn to elevate my playing?