Create a story or message for your song. Brainstorm and write a list of topics that you are passionate about writing and rapping. This includes love, rising from rags to riches, politics, spirituality, hardship, fame or any other theme that you wish to convey with your song. Avoid cliche themes such as having a lot of money and sex if you want to create a strong song.
Listen to a beat. Create your own beat with a keyboard and production software, or buy a beat from a website such as 20 Dollar Beats. Play the beat on repeat until you are able to catch the rhythm and create a flow. Hum the flow in your head as if you were rapping. Tap your feet, snap your fingers, bob your head or do whatever it takes to feel the rhythm. Pay attention to the mood and the tone of the beat as well.
Compose the first verse. Continue listening to the beat and write according to the flow. Write at least 40 bars (lines) for each verse. Begin and end each line on every down beat. Adjust the tempo of the beat if it is too fast or too slow. Think of a verse as fuel. The last bars of the first verse should drive and carry the song into the chorus.
Rap the verse aloud to the beat. Make sure that every syllable hits and flows. Continue rapping and tailor every line so that there are enough words on each line. Add or remove any words, if necessary. Every line should reflect upon the theme of the title and song.
Record and listen to the verse and beat. Jot down any keywords and ideas you have for a possible chorus. Loop the beat and verse over and over again. Think of words and a theme that reflect upon the verse and beat. Channel your energy from the beat and verse onto the notepad. Hum, bob your head and develop a groove for the chorus.
Write the chorus. This should be five to ten lines long. It can be rapped or sung, so think of how you want it to sound. Write the chorus at the climax of the beat. Most beats have a section for a chorus where there are several layers of sounds and instruments. Arrange various combinations of lines and words from the notes you created until you find a chorus that works.
Record and listen to the chorus. Loop the chorus section of the beat and say the chorus that you created. This is often the most emotional part of the song, so make sure to give it your all. Add or delete unwanted lines and make any adjustments, if necessary.
Complete the song. Use the power of your first verse and chorus to create more verses and a bridge. Extend the chorus at the end of the song, and layer it with additional vocals and harmonies.