Decide on the verse's form. The most common form in hip-hop music is the couplet form, or AABB. Some rappers experiment with different forms depending on the instrumental and sounds of the words.
Write to the instrumental's tempo. Listen to the nuances of the beat and melody to dictate the best approach to lyrically complementing the music. For example, an internal rhyme structure may sound more satisfying over a 60 beats-per-minute instrumental in order to take advantage of the slow tempo. Listen to the hits of the snare, as well. If the snare hits on the second and fourth bar of each measure, you could pattern the rhyme scheme so rhyming words hit at the same time as the snare or on every beat. Eminem's "The Way I Am" is a perfect example of this pattern.
Place stressed and unstressed syllables one after another. This gives the rhyme a bounce that makes the pattern sound more natural and musical. Tupac in particular was skillful in this regard.