Watch the >> Fretboard View online guitar lesson by Larry Carlton from 335 Improv
I always try to make my solos as "melodic" as possible, and having a firm grasp on the chords that I'm playing over is essential for me. I recommend the same for you. As you follow me through this course you'll note that I rarely think in terms of scales, parent keys or even progressions when I'm improvising.
Of course, I'm aware of all those elements but I'm really thinking about the specific chord that I'm playing over at the moment, and then -- just before I get there -- the next chord in the sequence. So, make sure that you are completely familiar with the chords that you'll be playing over before even attempting to improvise over them. This will have a huge impact on your improvisations.
Follow along with the notation as I run down a section from "Smiles and Smiles." Just listen and follow along the first few times and then play along with me. Be sure to catch that Bbmaj7 in the climb in the second 8 - it's not a chord that you might expect to see.
You also want to get intimately familiar with the head so that your lead lines make sense in the context of the song. A good melodic solo is related to the song's own melody. Even two tunes with exactly the same chord progression should get very different treatments when it comes time to blow over a chorus or two. As Thelonious Monk said, "Stop playing all those weird notes, play the melody!"