The sounds of the R&B singer vary from agile riffs to high belt. Finding a voice teacher willing to work technique and apply it to this material is tricky. Most teachers insist on working classical or musical theater material to build technique.
The basic technical skills the R&B singer needs are the same as any other style: solid alignment, great breathing coordination, facile articulation, and balanced registration. If your skills are solid, the R&B artist can seek a coach to help polish their style and material.
Sound: The R&B singer uses vibrato on the sustained tones in ballads but a lot of phrases are conversational and don't require vibrato. The lyrics are very important and the sounds of the voice need to vary to reflect the message. R&B singers use a microphone, so projecting the tone isn't as crucial as in the opera.
Healthy technique: R&B singers have to be versatile artists. An agile technique is a must to sing riffs and belt into the top part of the range. It's tempting to use full chest voice to sing this style, but balancing the weight of chest voice is crucial for your long-term vocal health. The ability to be understood without overarticulating is also crucial to the fast-paced stories in R&B songs.
Naming names: Beyoncé Knowles (remarkable solid technique and versatile artist), Maxwell (comfortable showing off his falsetto and mix), Rihanna (powerful singer, comfortable singing in her head voice and then moving right into a belt), and Usher (comfortable creating luscious tone as well as facile articulation).