It sounds cliche, but this is where success is found

No matter how much may be said and printed on the subject of methods to be employed in selling, every salesman when he fronts the buyer must fall back upon his own native ability. In almost every case he finds some new or changed condition not covered by his manual. He is also restricted and hemmed in by his own individuality. What might prove a successful method for one, would result in dire failure for another. Imitation is fatal. A salesman must look to himself. He should seek within for his difficulties, not without. — Henry Theobald