|
for trance stick to minor scales although I don't feel the need to focus on any chord progressions in particular... just play around with basic chord progression knowledge (Music Comp for Dummies)... sometimes you want uplifting, sometimes dark and brooding.
For techno, house and other genres, don't be afraid to try ANYTHING with even divisions of tone... in other words, scales with any number of notes divided up by double, full, half, quarter, eighth tones... Look up arabic, middle eastern song composition and you'll find they break up scaling into quarter tones.
On the other end you could use the 3-note, 4-note and pentatonic scales.
An example...
Root, minor 2nd, major second, major third, major third + 0.50 cents, major sixth, minor seventh + 0.50 cents, octave
Root, major 2nd, minor third, perfect fourth + 0.50 cents, tritone, tritone + 0.50 cents, minor seventh, octave
To get tones less than a semitone you obviously will need to do something clever with your midi roll / arranger 
|