The first thing to do is to analyze the music and find the functional progression, for instance D G C would be ii V I. From there you can transpose them to another mode, you could add extensions to the chords (for instance add a minor 7th, so that the ii is a minor 7th chord and the V and I are dominant 7th chords) you can substitute the chords (for instance you can substitute ii for a chord with a root a tritone away, making the progresssion bvim7 V7 I7 or substitute the V for its secondary dominant making it bvim7 II7 I7), you can extend the progression with other chords, you can alter the chords in different ways like making the I a sus4 chord, the possibilities are somewhat endless.