Each to their own, but I like the simple side of the theory that the modes are just 'major, but starting on the 2nd, 3rd 'etc. the Greek naming and way it is often presented (like earlier in this thread!) just confuse it for me.
Perhaps I don't know enough anout it and am exposing my ignorance here - but as far as I can tell, learn the major scale shapes across all strings, up and down, starting on different fingers etc. really learn it by heart (I remember some SBL lesson saying this and it stuck with me - suprisingly few bass players can flawlesley play a major scale on one string, or using open strings, or jumping from the E string to D string etc) . And then you have it really, just instead of where you were starting on the '1' of a major scale start/finish on the 2nd, 3rd, 4th etc. and get used to doing the 'shapes' from those starting points.
I
Don't
Play
Loud
Music
After
Lunch
The limitation to this is I only know how to play the modes when playing the shapes on the Bass, it'd take a lot of thought for me to translate that to other instruments or written notation.