If you've done exceptional work to convince a client that you are in his service and that his success is both your goal and your responsibility, you've gone a long way toward ensuring the success of this partnership. There are two more critical pieces to the mosaic that must be undertaken and monitored.
The first of course, is the implementation...the follow-through. Anything less delivered than as promised makes working with you a mistake, and makes you a liability. Needless to say, makes you NOT a great seller. The work really starts when the customer says "yes."
A Great Buyer holds your feet to the fire on your promise, your end of the deal. He metrics the progress against the promise, is involved in strategies and plans that require re-working because of unforseen but inevitable potholes. He paces and races with you from start to the finish line. A Great Buyer is a great partner.
A Great Seller must also "demand" the best from his client. He must monitor and metric the degree of effort that the Buyer expends to maximize the benefits, to the buyer, of the partnership. The Buyer's responsibility is more than to write the check when the invoice is delivered, just as the Seller's responsibility goes way beyond getting a signature on the contract.
"Mr. Jones, we need to...how can we?...what if we?...weren't you going to?...I thought we agreed that you would...etc." Wow, the Seller sounds just like a buyer. Only the great ones.
In an effective partnership, once the deal is made, Buyer and Seller are "in it together" and each hold each other's feet to the fire.
Love Your Work and Work Tirelessly
Communicate Honestly and Fearlessly
Serve, Don't Sell