Study the works of published poets to familiarize yourself with the different styles of poems and how poetry is used to describe the environment, relate a story or express feelings such as love, hate, confusion, fear, pride, happiness and sorrow. Just like with novels, the styles of poems that resonate the most strongly with you are often likely to be the best candidates for you to use as a model for your own creations.
Decide what you would like to write about and which poetic forms lend themselves to the mood you want to project to readers. If, for example, you want to write about nature, the simplicity of haiku allows you to paint sparse but vibrant imagery with only three short lines. If you have a wicked sense of humor, the distinctive rhythm of limericks might be a good fit. An old-fashioned romantic poem lends itself to a sonnet or rhyming couplet. Philosophical observations and short-form stories are frequently conveyed through free or blank verse.
Begin with a list of everything you want your poem to say. If you're writing a poem to express your love for a parent, spouse or child, for example, reflect on all the different ways they make you smile, the way you can always depend on them or favorite memories of time spent together. If you're troubled by the state of the world, identify the issues that make you angry, hurt and confused and how these correlate to events in the past, present and future. If you're writing a humorous poem about cooking and eating, compose a list of foods, cooking implements and cooking methods; you'd be surprised how many of these are easy to rhyme.
Meditation, music and solitary walks are a good way to clear your mind in preparation to write your poem. Poetry shouldn't be a stressful experience but, rather, one that you can explore when you're calm, relaxed and free of outside distractions.
Become a keen observer of your surroundings and how you interpret that world through sight, sound, taste, smell and touch. Keep a journal and jot down topics or phrases that lend themselves to poetic expression.
If you're having trouble creating a rhythm for your poem, try tweaking the words to fit the melody of a favorite song. Sing it out loud to hear how it sounds.
Don't be so concerned about forcing a rhyme that you lose the very message you're trying to communicate.
Just like a punch line, try to save the best phrase of your poem for last.