Usually, the music will come first and the lyrics will follow. Most of the time, the meaning of the song, lyrically, is like a puzzle that needs to be solved. I'll usually just start singing over the music and come up with a few key words and lots of gibberish. The idea for what the song will be about will usually present itself before too long. You just have to be good at sifting through everything for clues.
Some songs take months to complete and some come in five minutes.
It's staying open and positive, and not being afraid to try new things, that really help creativity and help to get the songs out. That statement is somewhat true, no question. I'm a firm believer that it acts on a much more subconscious level than that, however. I don't think that most writers set out to steal or copy from others, but every writer does have influences that they aspire to be like. I believe that everything that goes in will eventually come out.