Very interesting to read how people do it differently!
And that is exactly what i do.
Sometimes i write a lead melody first along with lyrics (that happens when i have a melody in my mind and i usually put lyrics to it right away) and then i either go to the piano or the guitar and then i find a good chordstructure. Then i will define the timesignature and tempo and record it with a click. When that is down, it is so much easier to hear more melodies that should be in the song while listening to the recording, as well as drums.
Another way is starting with a chordstructure on the piano. Then listen for a melody line, and put lyrics to that. I have a folder full of ideas to lyrics, and it happens many times that when i write them, in that moment i dont know how to use them, but maybe 6 months later i write a piece of music, and i go back to those lyrics, and they seem to be made for that song!
A third way for me is to make a riff on the guitar, or a melody, i then record it and find chordstructure to support it. I still have songs with no lead melody nor lyrics, cause i just havnt found the right thing yet, but i know it will come:)
As Magnus said as well, writing a rhythm first is also an effective way of doing it, i did it at the musicacademy i went to, and i was sceptical at first, but it really did work! And i got some good songs out of it!
So yes, a bit of strucure, inspiration and imagination is what you need:)
