Take a look at
this column by Bill Farquharson in
Printing Impressions that details what marketing has to offer sales. It's a lengthy column, but it might help you understand what your marketing person/department can do for you as a sales person and how to ask marketing for assistance in finding the right kinds of leads to make the right kinds of prospects that make long lasting clients. This author reminds us that marketing is a slow process and it takes time, but in the end it's well worth the investment of both time and money.