Walt Whitman honestly felt that the restrictiveness of the classic poetry form was a hindrance to his expression. Those who followed him refined the free verse form, making it the most popular with readers and fledgling poets alike. Finally, the Beat movement, led by poets Allen Ginsberg, Gregory Corso and Lawrence Ferlinghetti, brought poetry to the masses. Today's poetry is now being produced by students, doctors, factory workers, homeless people and any other walk of life you can think of. There are numerous poetry societies and amateur critiquing circles all over the world.
All good poems start with good inspiration.
Whatever the inspiration for your poem, be prepared to dig under the surface for the best material. We already know what a train looks like- you must use heightened language to put the reader on the train, with its whistles and noise and rhythms and everything. Poetry that stops at the surface is usually not all that impressive. Choose imagery and specific phrases that place the reader at a designated spot at a designated time. One of the great things about modern freeverse is the freedom to combine words in non-linear ways.