What camera settings do I use to photograph one of my paintings?

I have a Nikon D5100 and an oil painting that just finished drying. What kind of manual settings would work best to get the color and such right? Also should I use flash or go outside on a sunny day? A cloudy day?

Neither using flash or placing it onto the sun; use a soft light avoiding reflections, photograph it frontally to get rid of distortion. You don't need a close aperture, don't select the widest for focus accuracy and use a tripod better