Title your senryu poem. Human nature is the subject matter of a senryu. Find a title that clearly indicates what the poem will be about. If it is about human greed, title the poem "Greed." Single-word titles can be blunt and effectively capture the subject.
Write the first line of the poem with five syllables. An example opening for the poem titled "Greed" might be:
Money is the root
Write a line of seven syllables for the next line. Do not rhyme this line with the first. An example second line to the first line above:
But humans plant the seeds of
Add variation to your senryu by using irony, metaphor or even something satirical or humorous. While the subject matter is human nature, this doesn't mean everything needs to be dark or serious.
Write a third line of five syllables. An example, continuing from the examples above:
Evil money brings
Do not rhyme this line with any of the other lines. Keep the subject matter as human nature, follow the syllable patterns, and keep to a three-line count. This will allow you a wide spectrum from which to create your senryu poems.