Study and emulate rhythm-and-blues songwriting. Songwriters, like musicians in general, develop their skill and craft by studying and copying their musical heroes. The young Bob Dylan, for example, was heavily influenced by and indebted to Woody Guthrie. In a similar vein, rhythm-and-blues lyricists develop their own voice by first imitating their heroes. Louis Jordan was the most dominant figure in the early days of rhythm and blues and had a profound influence on Chuck Berry's songwriting. Study the type of rhythm-and-blues songs that you are interested in. Rhythm and blues incorporates a broad spectrum of musical styles from Louis Jordan to Fats Domino and Ray Charles, from Stevie Wonder and Aretha Franklin to Barry White, and from Beyonce and Alicia Keys to The Roots.
Write ideas and thoughts down in a journal. Ideas for songs may strike you at any time. It may be a turn of phrase that you hear during the day, it may be something you see on the evening news or it may be a visual image you unexpectedly encounter. Keep a journal with you and jot down ideas as you go about the day.
Find a writing style that works for you. Some lyricists prefer to write the lyrics first and then set the lyrics to music. Other lyricists prefer to write the music first and then write the lyrics that go with the music. The foundation of contemporary hip-hop style rhythm-and-blues songs is the drum beat or the rhythm track. The advantage of writing the music first is that the music itself creates a mood, as well as a rhythm and melody for the lyrics.
Decide what sort of mood you are aiming for. As mentioned above, the music itself creates a mood and it is important that the music and lyrics complement one another. At the same time, it is just as important to find the right lyric to express the message you want to share in the song. Many of Louis Jordan's songs are comedic and the lyrics are full of comedic ideas and double entendres. A typical example is "Ain't Nobody Here But Us Chickens." However, the mood of rhythm-and-blues songs is a varied as the genre itself. Rhythm-and-blues songs can be sweet and sexy, plaintiff and melancholy or somber and serious. Marvin Gaye's "What's Going On" is an example of a serious and somber rhythm and blues song.
Write a rough draft of the lyrics. Rhythm-and-blues songs typically have three to four verses or more and a chorus. The chorus is repeated several times during the song and is generally the part of the song that sticks in people's minds. Think of the chorus as the vehicle that delivers the message of the song. Think of the verses as vehicles that shed light or different perspectives on the message contained in the chorus.
Polish and fine tune the song. Once you have written the major lyrical ideas, it is time to add the final touches. Sing through the verses and chorus and listen to how it feels, flows and sounds. Perhaps you need a word with more syllables or less syllables to produce the best musical effect. Critique the lyrical content. Replace cliches and obvious word choices with something more interesting that will surprise and catch listeners off guard.