Another tip you might consider. If there is a really good account worth doing work for, on your second, third, forth, fifth time you call on them try taking in a box of donuts to the transportation supervisor as an example.. It's magic.
Also, sometimes you might face one, two, three, four or five "no"s. But sometimes the friendly fifth call might be a "yes" and develop into a great customer who will appreciate your persistance more than a lesser price.
Screenman once noted "Keep selling!"