Unless you hold a signed contract in your hand, sales forecasting has always been—and perhaps always will be—a tricky endeavor.

But should it really be this difficult?

To my frustration, among the many marketing and sales professionals I have encountered, most tend to make rough guesses—typically offering numbers only slightly higher than the previous year—and then secretly hope they have forecasted low, so that actual results can exceed expectations.

So, how do you navigate the balance between the "art" and "science" of sales forecasting?