Write down your thoughts in much the same way as if you were writing a poem in free verse. continue writing until you have brought your idea or thought to a natural conclusion
Arrange your lines into stanzas, the common ones are in quatrains four line stanzas, or sonnets, either Shakespearean, three quatrains and a couplet, or Petrarchan, an octete and a sestet.
Choose your rhyme scheme, the common one is a rhyming couplet where each two lines rhyme, called aa bb cc dd etc. Another more difficult but sophisticated rhyme is the abab cdcd efef rhyme scheme where each second line rhymes.
Once you have your first line write the second of rhyming one up to the final sound in the line. Now you need a rhyme so in your mind say the sound you need with each letter of the alphabet until you find a word or suffix you can work with, and jot this down.
Rearrange the line if necessary to make this word natural and the fitting word for the intended meaning. Repeat this process as often as needed. In some cases you may need to alter the first pair of a rhyming couplet.
Embellish your poetry by writing a definite rhythm into the words. rhyme sounds infinitely better if it has a definite metre and beat when it is read or recited. The common meter is Iambic Pentameter.