The romantic image of creators is one of drawing inspiration from the world and translating it at the piano onto staff paper. Perhaps you revise as you go, or in a draft process, but in essence you are creating in real time and putting it on the page.
I would like to make a case for brute force composing, though. It’s much more craftsmanlike – less artiste, more tradesman – but no less valuable an approach.
It goes like this. Assess your creative challenge in that moment – perhaps it’s a modulation from C minor to B-flat major. Now, make as comprehensive a list as you can of ways to effect that feat. Circle of Fifths progression. V-I cadences progressing by whole steps upwards. Pivot chords. Sudden modulation. And on, and on.
Make the longest list you can. And then assess every option. You might not need to fully notate every compositional option you’ve come up with in your brute force compositional process – some will eliminate themselves right away, and as you hone musical preferences, you will know better what you will like. Others you will have to fully compose in order to assess.
This process takes time, but it is often an effective way to create, particularly when you are stumped or when you want to try musical ideas that you might not ordinarily gravitate to.