How do you go about writing a song?

I am wondering about people's methods. Sometimes, I kind of scribble down an outline of what i want the song to be about, in verses but not poetically or anything. Then, i go back and use the same ideas but change the wording and come up with a rhyming pattern, etc. Sometimes i will have certain phrases in mind that i want to use and i will try to find a place to squeeze those in. Does anyone else have a better way of doing it?