What I do:
Usually I come to your studio. I do this because unless you just have a couple of paintings for me to photograph, it is easier for you. And also I'm curious; I like to see where you live and work. I like artists. I am one myself.
I bring a two strobe setup with a couple of large umbrellas. I shoot in raw format and
use Datacolor soft and hardware to insure true color. My workflow includes Lightroom
What is important in photographing art is true color and trueness to shape and dimension. If your painting is 4' x 7', the photograph will reflect that ratio