Why I don’t sell my Katherine Bernhardt painting at auction

Financial dilemma

I bought a beautiful Katherine Bernhardt painting in 2008 (for money that I had earned through a summer job). I have now decided to sell the painting to make room for other investments. A dilemma is whether I should sell it back to a gallery, sell it to a private collector or sell it at auction. Also, I must figure out how much to sell it for.