This will probably sound like an intro. Sorry ...
I have been singing all of my life but I pick 1974 as a starting point because that is when I started teaching myself guitar so that I could do songs. Picked up a family guitar that only had 3 strings on it and started plucking the arpeggio, by memory, from "Who'll Stop the Rain?" by Creedence Clearwater Revival. Most of my time has been NOT recording. So, I write, usually on a guitar, with the idea of performing live. And usually, it's kind of sappy folk 70's love songs, similar to Dan Fogelberg, though I was playing the entire Led Zeppelin catalog from Led Zep I to V (Houses of the Holy) at one point in time.
I don't write a lot but when I do, it flows through in a torrent and it's all I can do to get out of my own way and let it happen.
I worry about recording and mixing, later. You've got to have a song. If it is written well enough, I think the mixing strategy can flow from that.
At the same time, take inspiration from the oddest things, like an effect that leads into an idea. Or, do what I do, go to the circle of 5ths to give yourself a re-boot. Circle of 5ths is where you can start a melody or chord progression somewhere and the next one is 5 steps above or below.