Write down the gist of what you want to say in your poem, and expand on it in as many ways as you can think of. You won't use every single thing you write down, but this gets all your ideas onto paper and gives you a place to start structuring your poem. Think of the situation you're writing the poem about, the external factors affecting it, and the end result you want to portray with your inspiration. Think of inspirational quotes or metaphorical images to incorporate into your poem.
Begin structuring your poem so it has a beginning, a middle and an end. Don't worry too much about the number of syllables or the rhymes at this point, just get a solid, base structure. Include one or two inspirational metaphors, like the sun rising or spring coming into bloom, to symbolize things like victory after a time of darkness and defeat. Structure the poem until you have 12 lines that are relatively equal in length. If you want your poem to have a rhyming pattern, circle or highlight the words that rhyme with each other.
Count the number of syllables in each line of your poem and write that number to the side of each line. Notice your average number of syllables and whether or not you already have some sort of pattern forming. Decide on a syllable pattern to use throughout your poem.
For example, if you notice you have an average of five to seven syllables per line, you can write the entire poem with lines of five syllables or with lines of seven syllables. If you want to vary the number of syllables used, you could alternate the number of syllables in each line, switching back and forth between five and seven syllables. Another option is to write one verse with five-syllable lines, followed by a verse with seven-syllable lines.
If you want to write a free-form poem, ignore the number of syllables.
Look back at the rhyming words throughout your poem and look for words that rhyme with each other that can form patterns. Choose a rhyming pattern based on your findings. Some common rhyming patterns include ABAB CDCD, AB AB AB or ABA BAB. Adjust the rhyming scheme to fit how your lines and verses are organized.
Edit your poem until it fits your rhyming and syllable patterns completely. Use a thesaurus to help you find rhyming words or words with a different number of syllables that share the same meaning. Take your time and try not to get frustrated when you reach a rough spot or experience writer's block. When you finish it, read over it a few times to check for any errors.