As I say with every project: begin with free-writing. Grab your notebook and a familiar pen. Fill a page with your topic of choice. Seasons and nature are traditional, but the world is yours. With any writing job, especially one this small, write a lot about a little. Pick a tiny subject for a haiku and magnify it.
Now select from your page the elements essential to your topic. Look for contrast. See how an ant is tiny and easily crushed, yet can lift many times its weight and is dominating in large numbers. Note that a shark is speedy and ferocious in the sea, yet helpless and withering in the sun. Once you have found this juxtaposition and have brainstormed on both sides, you're ready to build.
In a syllable-dependent form like the haiku, dense words are essential. Find smaller synonyms for long words. Flip through the thesaurus until you find a monosyllable you like better. Capitalize on double-meanings. Choose words that echo. Does a ring on a finger make you hear the sound of a bell or imagine people dancing in a circle? What simple symbols have broader meaning for you and your readers?
Haiku's compact portability has been the key to its success. Across the world, people take a little time to build seventeen syllable landscapes. They are taught to young children. I wrote my first haiku when I was seven. Speakers of every language on the planet compose and share haiku.
The smallness of the world created by the internet has revived this form. Poetry communities of all types, including fans of the haiku, have formed across the web.
When the seventeen syllables of haiku met the 140 characters of Twitter, it was a perfect January-May romance. You'll find people sharing #haiku commonly, including @Twaiku and @Twaiku_poetry. Ryan Mecum (@MecumHaiku), author of zombie and vampire haiku books, often tweets haiku challenges. His Valentine's Day zombie challenge prompted me to write this:
I only have eyes
For you. The hearts were too ripe.
They were out of brains.
Not as deep and tranquil as the original masters', but fun exercise nonetheless.