There are lots of ways of approaching them. I like the approach Guthrie Govan spoke of in some video. This is just for common modes, based from the Major scale.
It’s just one note that changes to make all the different modes.
7 modes total (in this grouping) and the 7th mode is Locrian and fubar. So we leave that one out. Trust me, it sounds fubar.
The remaining 6 modes, 3 are Major and 3 are minor. All 3 Major modes contain ALL 5 Major pentatonic notes. All 3 minor modes contain ALL 5 minor pentatonic notes. You only have to add 2 notes to the pentatonic to get a full scale. And you only change one of those two notes NOT in pentatonic to make different modes. And by the way, that note that got changed is the money note, it defines the mode.
The Major modes:
Ionian - the Major scale
Lydian - Major scale with a sharp 4th
Mixolydian - Major scale with a flat 7th
The minor modes:
Aeolian - the natural minor scale
Dorian - minor scale with a sharp 6th
Phrygian - minor scale with a flat 2nd
There was a post by
@Nitrobattery (guitar instructor) on how he assigns a mode to each of the seven 3-note-per-string patterns. Then you just move those around for what key you are in. Since those patterns never change and always connect to each other the same way, you should always be able to find your way around. For all I know he did that itt considering its age.