The most important ingredient in a Shortsale is your patience:
We tell Clients this, and it doesn't seem to register.
If you have the slightest urgency, do not attempt this.
Then get yourself a Buyer's Agent familiiar with SS; it doesn't have to be the World's Record Holder in Shortsales, (with my wounds I would be a contender), this is not that different; just someone experienced.
Then, listen to them.