We briefly mentioned “Suzanne” by Leonard Cohen earlier. Aside from the religious references, it was also originally a poem Cohen wrote and published before the song was ever recorded. Try writing a poem purely on pen and paper, without worrying about melody or rhythm at all. Once you’ve got a solid draft, try setting it to music. Ultimately, you might need to be inventive or make some changes to make everything flow nicely, but this can produce good results.
In the diagram below, the left side demonstrates how two in-phase waves sum to an amplified resulting signal. The right side demonstrates two precisely out-of-phase waves are attenuated to silence.