Guitar scale practice: what should I learn after the pentatonic scale?

Questions
1

I’ve been playing guitar for 2 years. I’ve learned the 5 positions of the minor pentatonic, but I’m stuck after that.

What should I learn next? The things I’m considering are:

  • Dorian (I’ve heard it can be used over the ii chord)
  • Harmonic minor
  • A scale usable over the Canon progression

Also, I still don’t really understand the relationship between scales and chords. In the key of C major,
when playing ii-V-I, which scale should I use?

2

Hi! After the minor pentatonic, the natural next step is the full major scale,
not the modes. The modes come later.

For the ii-V-I in C major, you can play the same C major scale over all three
chords (Dm7, G7, Cmaj7) — only the tonal center changes. It’s the famous
chord progression in C, the basis of everything.

3

I’ll add to what was said: don’t learn positions separately — learn the scale shape
on the circle. Dorian is the same C major scale, just with a different
tonic (D). Once you see that once, all seven modes fall into place
on their own.

Put harmonic minor aside for now — you’ll need it less often than it seems.