Take good pictures, test it to make sure it works, post it on Ebay. Check a couple of recently sold examples to get a feel for what they're going for, and pick your price accordingly. When you ship it, put it in an anti-static bag, in a box loosely packed with crumpled paper so it can't knock around, but isn't stressed when you close it up. Preferably, if you don't have the existing box and packing material, cut a strip of cardboard and wrap it over some bubble wrap at the ends of the board to let it "float" by pylons. This prevents any damage at the edges, and gives it a cushion. Make sure the middle of the board does not bear any load (excessive packing, or potential fulcrum point), or else you will bend and possibly snap the board if it's under stress during shipping.
Most importantly, for the love of all that's vintage, do NOT put the board directly in a plastic bag or bubble wrap and mail it in a padded envelope.
What else would you want to know?