I don't write much but do have 2 pieces copyrighted. I follow a certain process. When an idea comes into my head I do almost nothing. I may sit down at the keyboard and fool around with it for a few minutes. I don't write anything down or record anything. I wait until the next day. If I can remember the melody, chord progression, etc I get started on finishing it. If I can't recall anything it wasn't worthwhile.
I have only written a handful of songs or so, and they have been pretty over thought.
But for what it is worth, I am a lyrics first guy.
It starts with an idea for a line or a rhyme within a theme that would make a song.
I then think up more ideas for lines/rhymes that would fit the theme and touch on aspects of it that could be addressed in the song.
If I have enough, I start putting structure to the song. This is tricky. Unusually want to have like 3 verses, and I might have 6 lines. Gotta find a way to connect the dots. What goes well in first verse, what goes well later. How to get the number of syllables to be close enough to fit.
If I manage to write acceptable lyrics, chord progress comes next. I usually have some idea of how I want the lyrics to be sung. I will try the part I feel most strongly about over different chords, untill I find one I like. Then I look up common chord progressions that would fit, and try them out. Sometimes the pieces fit together
Just FYI @MegaRhyme , you do not have to officially copyright your music. The moment you create your music is the moment copyright begins.
My process: I have been writing songs on guitar for over a year. but I've only been playing for about 2.5 yrs. Professionally, I've been a wordsmith of sorts, so I start with writing the lyrics, like @UkingViking . For a while I could only come up with lyrics, and had about 25 songs written, but nothing musical attached to the lyrics. I've never had musical training and can't read or write music, so my process is probably different from those who can.
The theme of the song and the words frame the overall feel or vibe, and I start to noodle around with a melody. I have a small keyboard which I don't know how to play, but I know how to pick out notes. Once I start singing something I like, I record it. Just use the mic tool on my laptop. Then I listen to it over and over until I get it in my head. Then I start to play notes and chords on the guitar to go with the melody. Record the pieces again. Sometimes I'm happy with what I've created and I play and record the entire song. It's very rarely completely done at that point, but sometimes it's close to the finished product. Usually, though, I put the song away for a couple of days or weeks and come back to it and listen to the recording(s) of I've done, because sometimes I don't remember the melody at all. Then I edit, edit, edit, both the words and the music, continually recording through the process.
When I'm all done, I do an audio recording in addition to a video recording that I post on another guitar forum that I'm on. There are a bunch of songwriters on the Forum, some who have their songs on CDs or on streaming services. And sometimes I get feedback on the songs. It is can be ego crushing to get unsolicited criticism about your work, but I always do my best to be open to it.
In my other Forum, there is the songwriting section plus monthly Zoom VOMs (virtual open mics) where we play our songs and talk about songwriting. Don't know if I'm violating policy, but it's justmusicgeeks.com
Just want to add that I read so much at work, that I've become reading averse. So I listen to lots of audio books. Sometimes there's a phrase or metaphor that I love, and I'm always squirreling away those tidbits to turn into future lyrics. I highly recommend listening to audio books if you're ever stuck for lyric ideas.