Sam, there are a lot of people here that are going to think your request is out of line, lacking further details.
A lot of new artist will paint from pictures of the old masters that are public domain images. If you would want to then sell prints from those images you would be clear of any copyright concerns. However even if you attribute the scene to the original artist, this will still be frowned on by a lot of people here.
I sell Old Masters reproduction and I get flack all the time for it. I am an old curmudgeon and couldn't care less, you on the other hand, assuming that is a pic of you in your avatar, are young and still learning and may need to be more sensitive to the shallow minded opinion of others.
Of course, if some one sends you an image and says paint it, then none of this applies. lol
Best of luck to you.
