A lot of concepts in this one I love it!
I'd like to begin with Voice Leading. Now there are various philosophies behind this practice, some strict, some lenient, some complex, and some simple. I'm going to lightly get into the lenient and simple as this is what I prefer, but if you choose, you can discuss further with your friends and I highly suggest that you do so in the "comments" section above. I'll be hanging out with you guys there as well and would love to explore this with you all a little more!
Voice Leading simply put, is the Connection of Harmony Through Melodic Lines and what this means on a very basic level, is that you should be aware of the movement of the melody or highest note, pitch wise, within the chords your are playing. What we are trying to accomplish, is the smoothest possible transition from chord to chord and usually, BUT NOT ALWAYS, this means that the melodic intervals should be closer together and contain a theme or Motif.
If this sounds difficult, well, sorry to say, it really can be but the general practice shouldn't be. To begin with, just listen to and watch the chord progression as you play it and ask yourself these questions
1) Is your fretting hand making big jumps up and down the neck when you change chords?
2)Do your chord changes sound disjointed and incohesive?
3)Are you struggling to find the right voicing and therefore settling on a more familiar chord shape?
If you answered yes to any of these, and I still do to this day, you may want to Spend More Time Experimenting With Different Chord Shapes, Inversions, and Substitutions. Even simply taking a chord shape that's familiar to you and changing the Melody Note to sound better in between the adjacent chords of the progression you are playing will begin to improve this technique and develop your ear.
Now some of you big brains may be asking, "Well I can move the melody around, what about the other end of the Harmonic spectrum...The Bass Line?!". Great question but since I don't want to further confuse you, I will just tell you that consideration for the ENTIRE CHORD or HARMONY is called Counterpoint. Again, I highly suggest discussing this amongst yourselves, but only once you've attained clarity with Voice Leading. More on this later.
For our next topic that Papa Gates touched upon in this lesson, let's switch gears a little and go back to Substitutions and more specifically, our Tritone Substitution. Simply put, a Tritone Substitution is when you substitute any Dominant chord for another Dominant chord a Tritone away. You should know this interval by now but if not and you are jumping around the lessons, it's a flat fifth, raised fourth, six half steps, or three whole steps away(all of these are the same distance).
Most musicians mainly use the Tritone Sub in Jazz and I do as well as it is a VERY common Chord and Melodic Substitution for the "V" and "VI 7" in the famous I VI ii V Jazz progression called the Turnaround, BUT, I use this quite a bit for Avenged Sevenfold as well.
For example, we use a progression in D minor quite often where we sub an E flat major chord for an A major resolving back to D minor. The whole progression looks like this, i III ii bii7(sub for V) or Dm FM E7 Eb7(sub for A7). The E7 is actually a sub for E minor7b5 which you can do do for any chord at any time really. More on that for later because MY GOD, this is WAY too much for now!
Now when you come across these Dominant 7th chords, especially as Tritone Subs, you can play the 4th mode of the Melodic Minor Scale called Lydian Dominant over them to get some really "Out" tension before resolving back to the "I" chord.
We are gonna need some serious help from all of you for all of this! It goes against my better judgement to introduce too much bonus material especially as advanced as all of this is, BUT, I really do believe in your ability to help one another so go prove me right and upload videos to the "Lesson Comments" section below of your questions, ideas, demonstrations, and creativity!