Select the beat you'd like to use. Audio bundles are widely available for purchase or download, as collections of rap beats are commonly used by music creators. Occasionally, rap artists make their beats available for download in order to encourage re-mixes and adaptations, although this is generally rare.
Decide the theme of the song, choosing from such common ideas as betrayal, love or growing up. It's useful that the theme of your song inspires you and that it naturally provides you with ideas for lyrics.
Brainstorm the lyrics to your rap song, which may take several hours or days until you begin to feel happy with what you've written. If you intend for the song to have a particular rhyming scheme, this should be reflected during your lyric-writing process. Consider including metaphor (whereby you compare two unrelated things without using "as" or "like", such as "You're the water in every forest stream") and symbolism (in which a lyrical element is used to represent something else, such as "You buried your head in the sand," which might represent a person choosing to remain ignorant).
Experiment with different singing styles and vocal ranges. Although it will vary depending on the type of song, it's useful to make the song vocally dynamic by signing certain sections in different styles, such as loud/quiet or fast/slow.
Create a chorus, which is typically a memorable line of the song that is repeated several times for effect, followed by a brief vocal break.