October 2015. After nine and a half wild minutes of outbidding, Modigliani’s Nu Couché was sold for 170.4 million dollars at Christie’s NYC.
If you happen to find another Modigliani in your basement, I am very happy for you. I mean it.
Now, picture the day you’ll sell it. You probably won’t want to split with an auction house- fair enough. 
In this case, you might want to consider some points:

1. Check the product: make sure it’s proper and undoubtedly true (labels, signatures, paperwork) – and price it right.

2. Find prospects: it’s who you know. The better contacts you make, the more interest you’ll raise. 

3. Professionalism and personal trust: nothing good ever happens when any of these two are lacking at any point of the “chain”.