Steep in classic compositions of jazz and the blues. Modern-day R&B works in response to such tunes as "God Bless the Child" and "Is You Is Or Is You Ain't My Baby?" Track down the lyrics to the songs that move you most, and write them out yourself, more than once. Let your fingers and brain experience the creation of strong writing.
Monitor the Billboard R&B/Hip-Hop Charts on a weekly basis. Examine the lyrics of those songs which consistently rank in the top ten or twenty. Learn the biographies, discographies, and music history of the artist, in addition to their production team.
Delve into the music of Grammy-laureled titans like Stevie Wonder and Ray Charles. Analyze the winners of R&B Grammys and listen to their CDs and songs on repeat. Transcribe the lyrics to those songs as you hear them, not from the disc jacket. Exercises like this will help to lend a sense of craft to your own writing habits.
Write at least one song a day, every day. Disregard the quality of each day's song, and get into the habit of writing for writing's sake. Collect your songs weekly and pick a few to revise. Avoid fascination with your failures and write no matter your mood.
Locate other writers, singers, and musicians to collaborate with consistently. Field your favorite original compositions to your crew and take in their opinion. Hear how your lyrics play to music, through another voice. Understand that music doesn't live on the paper, but rather in the people who enliven it.