Lurking within the tunes that you already play are ideas waiting to be used.
Take the standard Night and Day for example.
A common way to approach improvising on that is to work out what key it’s in and what scales to use. But pretty soon, all your improvisations and arrangements begin to sound the same. The same sounds, the same licks, the same SOLO.
Now Night and Day is full of opposites.
Watch this classic video of Fred Astaire singing this tune:
Maybe* Cole Porter took the idea of obsession and this is what he came up with.
The singer, Fred in the video, is obsessed with Ginger.
Check out the lyric: Beat, beat, beat, drip, drip, drip, tick, tick, tick, you, you, you.
That’s pretty obsessive, right?
So Mr. Porter uses repeated notes, mirroring that feeling. He’s thinking about her all the time – ALL NIGHT and ALL DAY! Those crazy 30s types :)
The melody to the Night and Day part (in this video it’s in E major) basically starts on a B and goes down a minor third to G#. When it moves to the bridge, the melody goes the opposite way, B up a minor third to D.
The chord progression goes: C∆ B7 E∆. Some people use F#-7b5 B7 E∆. What’s going on there is the F#-7b5 or C∆ are being borrowed from the parallel minor key, E minor. It’s a device called Modal Interchange.
Opposites again. Night and Day: Major and Minor.
The modulation in the bridge goes to G major, which is the relative major of E minor, and switches between E and G major, so it’s still sort of moving between E major and E minor.
The lyric uses opposites too: ‘Night and day, day and night’, ‘the roaring traffic’s boom, in the silence of my lonely room’, ‘beneath the moon or under the sun’, ‘near to me or far’.
Melodically, you could say he pits the use of repeated notes (the intro and start of the A section) against the descending chromatic melody (‘whether near to me or far it’s no matter darling, where you are, I think of you’).
You might say the repetition is the obsession and the chromaticism is the torment.
Also, overall there’s a juxtaposition between the general falling chromatic melody and a hidden ascending melody that loosely goes B D D# E. (B on the A sections, D at the start of the bridge, D# ‘love to you’, E at the end)
So now you know all that, you could take any one of those ideas and use it to write a tune, or maybe it might help with improvising on this tune. So you can play from the feeling, or any of those ideas: opposites, contrast, major/minor, ascending/descending, repetition/chromaticism, obsession and torment!
Maybe that’s a more interesting place to start from than, ‘I’m using C lydian and then the altered scale’.
So, when somebody asks you, ‘What are you using on the A section?’, you should say, ‘Obsession and Torment’.
*Ok, maybe he didn’t think any of this stuff, and it’s all analytical nonsense. That said, if any of this nonsense makes you write a tune, or play, or think differently, then it’s useful nonsense.