This is the technique that I use to easily get chord progressions for West Coast Instrumentals.
1. First you need a starting melody.
You need to come up with a melody that will serve as a base for your chord progression. Preferably something relatively simple.
2. Next, you need to build chords.
For every note (or some notes) in your melody you will need to create a chord based on that note. Basically what you need to do is to use a chord that has your base note in it. For example of you have an A as a base note, and you are in the A minor scale, you can use the following chords:
– A minor (A-C-E)
– F major (F-A-C)
– D minor (D-F-A)
It is best that you use the chord on the root note (in this particular case, the chord on the root note is A minor). However the root chord doesn’t always sound good, so you have the two other options.
3. Chord inversions
To make the transitions from one chord to another sound better, you might have to invert some chords. In simple terms, what you need to do is to transpose some notes from your chords either up or down by one octave. A personal rule that I have for this, is to make it easy to play if you were to play the chord progression on a piano. Basically minimize the motion that a player’s hand would have to do in order to play your chord progression. So no big jumps on the keyboard.