The structure is governed by laws of logics, but writing, I mean relay good one, is a mystics.
I don't know how it happens. The inspiration just come and then I do it same way as I breath. The music helps me to catch up. Each one can develop its trigger.
On the other hand, inspiration without structure will not lead you to far. You can write few paragraphs out of nothing but when you don't know what next thing you need to write you will fail.
After all, this is an academic writing. You are not writing just to write, but to inform, and, thus, structure is the basics.
Learn it first. There are a bunch of on-line courses about this. I was just thinking to inspire you.