it depends. sometimes I sing something, sometimes it's worth trying to totally remember it, so I'll repeat it until I do.
Sometimes if there is a lyric, that can come attached to a tune. then I arrange it in my daw, decide on a sound for that, which is going to inform the whole attack and envelope of what happens, the 'time'.
more complex ideas, I started with a sound, palette of sound and decorated it, by improvising in my daw. and moving things around on the timeline, 'editing'.
I do not write on paper any more. the likelihood of hearing that has never been good, and it would be a total drawback for me to do it.