An affluent customer wants to invest in art. What 'Top 3' Resources would lead to reaching highly informed decisions when finding art/artists?

Conversely:

An 'unknown' contemporary artist discovers they are literally the only person in the world who does what they do, and wants to sell to a highly specific segment of affluent customer. What 'Top 3' Resources would greatly aid in understanding this customer & their needs?

Also, What 'Top 3' Resources should this artist consult immediately if they are serious about positioning their body of work as 'no-brainer' investment?