I learned while in university that just sitting down every day and writing something is the way to go. I never need "inspiration", my brain just goes into composing mode and ideas start flowing. But it took a few weeks before that happened.

As for the actual process, I ten to write whatever idea I have down, and see how far it takes me. If it starts veering into something I don't like, I save the file as a new version, delete the part that I didn't like, and start on a new path. In the end I'll have something like 10-20 different versions, sometimes I'll go back to an older one with fresh ideas and continue on a new branch, etc. More than a couple times I'll marry two versions and have the final product nearly finished just by doing that. If I get stuck, sometimes I'll just repeat a section with different instrumentation just to get a fresh take on it which will jog some new ideas.

There are also times where I think strictly "logically" or structurally about a piece. Let's say I've got a nice A section and some nice B section but no way to join them. Then I can reach into my proverbial toolbox and write something that I know will work (a short fugue-like bit, harmonize things to transition smoothly, etc). This is something I enjoy doing because it's like I create two puzzle pieces and have go figure out how to fit them together.

ETA there is a lemmy instance dedicated for music producers, composers, etc, lemmy.studio!