Vocal/guitar duet classifieds

carlos

It seems most of the ads for guitarists around my area (London, UK) are to support a singer in a duet. Usually keywords around those ads are neo-soul, r'n'b. Not trying to be cynical but in those genres guitar is relatively unimportant or altogether missing so it'd seem a tall order to carry all the musical load on just the guitar. If anything, a bass or keyboards player might be more suited to those duets?

What do you think? How would you approach an ad like this? What would you practice and prepare? Some of the voices in these ads are really wonderful and I'd love to get involved but am a bit baffled what to play, and how to to approach it.