1. Start with a 2-5-note pattern that sounds cool.
I usually find these in random places. Some of my themes have come from jam session mishaps, Brahms’ sonatas, finger exercises, a rad riff I stole from someone else’s tune, or weirdo note patterns that no one else has used and so I decide to do something with them because they’re completely unique and un-used.
2. Have a particular “sound” for the tune in mind.
For instance: a super happy Scottish 1-4-5 tune; a heavy, Irish, minor 1-b7 tune; a driving major Mixolydian tune; a way-too-fast Bluegrass tune that stays on each chord for way-too-long; or maybe a drone-y old time-y tune with that distinctive usage of only 3 or so notes.
3. Play your note pattern with a groove that fits in with your “sound”.
Usually you’ll have to loop it a couple times, but the idea is, at some point, to naturally start going a direction for the next couple notes or phrase. Sometimes I’ll hear it going in an upwards direction or a downwards direction or it’ll be a twisty melody that stays near the other notes. Either way, by looping what you DO know, you set yourself up to hear the next couple sections.
4. Continue with step 3.
Remember how the phrasing goes in a fiddle tune. The first and third phrases are the pretty much same; the second phrase leads into the third phrase; the fourth phrase leads back into phrase one, and then later into the first phrase of the next part. You’ll want to make sure that your composing isn’t random…
5. Only do the first three phrases for now.
Make them interesting. If there are any cliché note patterns, switch them out for something more interesting; a note grouping that no one has used before.
6. Finesse the connecting notes between phrases.
Again, avoid overused connecting-note patterns. Think of something weirdo that creates the right kind of tension for the phrase being lead into and for where you are in the tune.
7. Work on the fourth phrase.
This one is special because it’s basically your main tension-builder of them all. The entire fourth phrase should basically be very different from the last three. It serves as a cool lead-in to whatever is coming next. I like to use syncopation, rhythmic dissonance, tension-notes, weird chord progressions, and other cool stuff to create this fourth phrase. My process for it tends to be more intellectual than strictly musical, and I use what I know about music theory to make an ideal connecting phrase that has a lot of interest for the listener. Usually you can tell a song was written by me when you listen to the unusual fourth phrases.
8. Write the B-part.
9. Make the final tag (/phrase-leading-back-to-the-A-part) an awesome fireworks display of compositional concepts.
Similar in regards to creating the fourth phrases, but a little more over the top.
10. Write a chord chart.
In my experience, back-up players don’t usually play the song how you heard it in your head, so they need to be told what chords to play… Never leave it to them to figure out for themselves; the result is usually not the “sound” you had in mind. So don’t give them the opportunity.
11. And then you’re done.