There's no tried-and-true method though. Plenty of artists write the lyrics first. Often, its a collaborative effort, with one person coming up with lyrics while another comes up with the music, or a bit of both.
It can also be a cumulative process... artist gets an idea for a song... maybe just a subject matter or a few lyrics... then a melody idea forms, then, more lyric ideas, then back to developing more music... verses and choruses start to take shape. Now maybe you've got someone who can play a very simple version of the tune on an acoustic. Producers step in, and the whole process starts over again, until the final version of the song is reached. Sounds convoluted, but lots of great music was created this way. Its often why some albums can take a long time to record. If you get a chance, watch the documentary on Fleetwood Mac as they wrote & recorded "Rumors"... gives a good insight into the inspiration, song writing & recording process.
