I like to create the music first and then based on what I’ve come up with I will decide if it’s an instrumental or something that inspires some lyrics. I love to improvise and study theory so I think that makes it easier to come up with chord progressions.
I don’t need to feel inspired when I start, I will use anything randomly to get me going it may be a date, a serial number on the back of the guitar I’m playing, A UPC code on something etc. I take the numbers and turn them into intervals. If there isn’t a 1, I add it and randomly pick a note to be my 1. The key may change a couple times as I work to develop this into a song idea by moving my root. I find that as the idea develops how you’re feeling at the moment will come out in the song without you having to give it any thought the song just naturally takes on your emotion.
Here’s an example (I hope I get this right trying to type it out quickly) , today’s date 6/24/2020
I’ll add a 1 for our root, and we’ve got 6, 2, 4 for additional intervals or chords for our progression. This song could be a Major or minor key. I usually look at the intervals and compare them to the modes to decide how they will be played. Based on these intervals I would would make a song in a minor key because of the 2. That two is a characteristic interval for Phrygian when played as a minor 2nd. Add the minor 6th, and the perfect 4th… and we’re well on our way.
I may decide to add more intervals in to “force” the music to dictate Phrygian by adding the missing intervals with harmonies, bass, maybe keyboard, whatever or just leave it a little open. While there are options available other than Phrygian because our chosen intervals don’t dictate it…Locrian or Phrygian Dominant, blah blah blah, we’ll stick with Phrygian.
For simple fun here we’ll call it B Phrygian… works nice for a 7-string in standard tuning, and simple for others to play over… If in doubt, just play a G Major scale over it and you’ll be fine because we define B as our root as we develop the idea in a backing track.
B Phrygian notes are :
B, C, D, E, F#, G, A
Our chords will be based on the intervals and the triads for each based on the mode
i - B minor
II - C Major
iv - E minor
VI - G Major
Play with those Chords and come up with a progression you like, add more or take away… there are no rules, play B Phrygian with it… if it doesn’t sound right you’ve changed something that is no longer B Phrygian, keep going and see where it leads you. This is just a start, this will often lead me off into something completely different but it was what I used to kick it off.