1. The root note (or the tonic or the “1”). This is the “home” note in any given key. This is the note that sounds the most stable or resolved. All of the other notes have a certain sense of gravity that pulls toward that home note.
2. The root triad, built from the 1st, 3rd, and 5th scale steps of the key or mode. In major modes (ionian, lydian, mixolydian), these are the 1, 3, and 5, producing a major triad, and in a minor mode (dorian, phrygian, aeolian), it’s 1, b3, and 5. All of the triad notes sound pretty stable and “home-ish,” and provide good landing points for melodies when improvising or composing.
3. The pentatonic scale. If you add the 2nd and 6th notes to a major triad, you have created a major pentatonic scale. Note that these notes, 1 2 3 5 6, are present in all 3 of the major modes (ionian, lydian, mixolydian). If you add the 4th and b7th to a minor triad, you get a minor pentatonic scale. All of the minor modes (dorian, phrygian, aeolian) contain the notes of the minor pentatonic scale (1, b3, 4, 5, b7). Pentatonics are very easy scales to improvise with, and guys like Eric Clapton and Dickey Betts have built entire legendary careers using little else.
4. The major scale and its modes. If we simply add the 4th and 7th to a major pentatonic scale, we now have a major scale. If the 4th is raised 1/2 step (#4), this gives us the lydian mode. If the 7th is lowered 1/2 step (b7), we have the mixolydian mode.
5. The minor modes. While there are several different minor scales that exist, if we think of dorian as the most common (which is arguably true in improvised music), we can take the minor pentatonic and add the 2nd and 6th to create the dorian mode. If that 6th is flatted (b6), we have the aeolian mode, and if both the 2nd and 6th are flatted, we have the phrygian mode.
6. The non-diatonic notes. With any of the modes, we have 7 notes. And remember, there are only 12 notes total. So the remaining 5 notes that don’t belong directly to the mode–the “non-diatonic” notes–are the most dissonant, but can still be used in most any context, if you know how to handle them. Most often they are used as “neighbor tones” and “approach tones” to lead the way to chord tone.

So you can visualize this “hierarchy” like this:

The idea, then, is to start by pinpointing the root notes for the mode you are playing in. Then, map out the root triad, either major (for ionian, lydian, mixolydian) or minor (dorian, phrygian, aeolian). Then, map out the corresponding pentatonic scale while still keeping an eye on where those triad notes (chord tones) sit within the scale. Finally, add the last two notes to create the mode, keeping in mind that those two notes are the notes that, when added to the root triad, give each mode its unique character.

With this concept of building off of the root note, and then the triad, we stay grounded in the core sound of the mode, and we see how all of the other notes function in relation to that triad. Isn’t that better than just learning a bunch of dots in a diagram?

Now, if you want to truly master the modes, I think it is well worth taking the time to go through the HCG Modes Workshop to get a thorough understanding of how the modes work.