Modes and chords

Major modes: Ionian, Lydian, Mixolydian
Minor modes: Dorian, Phrygian, Aeolian

Since Aeolian and Ionian are just the natural minor and major scales, you already know where they work.

For the others, it'll sound most "modal" over a "modal progression" - a vamp that does not include a dominant 7th chord.

If you're working over jazz progressions, you can fit modes to chord alterations....

Lydian has a #4 compared to the major scale. If you see chords with b5 or #11, they'll work there.
Mixolydian has b7 compared to the major scale. It'll work best over dominant chord sequences.
Dorian has #13 compared to the natural minor. That's found in the melodic minor - if you see the melody in standard notation has lots of accidentals, and the progression is minor, it's probably a good choice
Phrygian has b2 compared to the natural minor. If you're in a minor key and see b9 chord alterations, same thing.

That's not meant to be comprehensive - just a 'cheat sheet' of observations to get you started. The only reason for using modes is to get a different sound from your melody, so the only real long-term solution is to be intimately aware of what the differences in sound are.

Thanks Noatboat..... though that mostly went over my head, I don't think I even know a b5 chord unless I know it without knowing it. These topics always give me a headache. Maybe I should have bought your book rather than a new guitar.

Ive found myself able to fit in dorian to bog standard blues and rock though with no difficulty, and obviously I can use the major/minor scale but I don't know where the rest fit in - in my life.

Perhaps the best way to understand modes (at least for me) is to think about them like scales. This article helped very much to me:

https://www.guitarnoise.com/blog/everything-about-scales-part-6/

I like that because in it we just play the modes in a key we chose, my old teacher numbered the modes and then said something like to be in this key we add this to that and try and make nine or some rubbish like that...... I had no clue what we were doing or why we were doing it. If he had just said "play a major scale - now sharpen the fourth" or whatever I would have seen what the hell he was talking about.

The other thing he could never answer - and that's what I'm driving to in this topic is when it is appropriate to use certain scales.
I am beginning to think in rock and blues, it's not really all that useful.

Perhaps the best way to understand modes (at least for me) is to think about them like scales.

I agree. Unless you're playing music where the mode has a wider function (like in modal jazz) modes are just scales.

You may find Chapter 1 of my scale book useful. Then again you may not... but it's free so it comes with a 100% money back guarantee :D :

http://www.scribd.com/doc/87559596/Scale-and-Arpeggio-Resources

It might also help you see what people are talking about when they talk about b5s and ninths and so on.

Unless you're playing music where the mode has a wider function (like in modal jazz) modes are just scales.

Even if you're playing modal jazz, modes are just scales.

Even if you're playing modal jazz, modes are just scales.

Indeed; all I meant was that in modal jazz we might want to consider the mode to be something extra in addition to the scale it undoubtedly is. But there the word "mode" is being used a bit differently anyway.

I am beginning to think in rock and blues, it's not really all that useful.

I wouldn't think that.
Modes are just different sounds to get into besides just the common Major Scale and Minor scale sounds.
Blues is another way to go as well. They're all options and sometimes they overlap. That's all.

First of all.
Let's see the notes of C Lydian.
C-D-E-F#-G-A-B
1-2-3-#4-5-6-7
C Lydian can work over a C bass, can work over a C Major triad (C-E-G) or CMaj7 chord (C-E-G-B).
Sometimes in constructing a one-chord-vamp we can add to the chord the #11(#4) which is considered the characteristic note of C Lydian. So, we can use the chord C Maj7 (#11) and start playing our favorite C Lydian licks.

For finding out diatonic progressions that C Lydian can work over, we will use the harmonization of the corresponding Major scale. C Lydian is the 4th mode of G Major scale. The chords of G Major are
G-Am-Bm-C-D-Em-F#dim
Theoretically speaking any combination of the chords above can give progressions that C Lydian can work over.

This is one of my lessons that analyze a bit the use of the Lydian Mode over an excerpt of a standard chord progression. The lesson is not focused in Lydian mode but can give you many ideas on how to use it.
http://www.lost-in-guitarland.com/guitar-chord-progressions-4.html

just a suggestion, not to take away from good previous suggestions, it's been my experience that the more perspectives you hear it from the more likely one is to click, so with that in mind...

one thing that helped me learn the sound of the modes
was to just think of it like this:
1) harmonized chord scale in c - Cma7 Dmi7 Emi7 Fma7 Gdom7 Ami7 Bmi7b5
learn those chord shapes
2) order of modes: C ionian, D phrygian,E dorian, F lydian, G mixolydian, A aeolian, B locrian
3) I would record a sort of 'drone' backing track using one of the chords and solo over it with associated mode until I was comfortable with the sound.

lets say you only know one scale shape... c major -
play c major against cmaj7 = ionian
play c major scale over dmi7 chord = d phygian
play c major against emi7 = dorian
play c major against fma7 = lydian
play c major against gdom7 = mixolydian
play c major against ami7 = aeolian
play c major against bmi7b5 = locrian

then take the opposite approach and learn the differences in intervals:
play c major over cmaj7
play c phrygian (Bb maj scale) over cmi7
play c dorian (Ab maj scale) over cmi7
play c lydian (G maj) over c maj7
play c mixo (f maj) over c dom 7
play c aeolian (Eb maj) over c min7
play c locrian (Db maj) over c mi7 with flat 5

as with any single approach there are limitations to this approach, but the best approach is the one that works for you.