You do it in the same way you forecast sales in any operation. Essentially, you take the previous year's sales; analyze the market to see if any changes, such as new competition, are on the horizon and what their effects might be; apply any new sales initiatives you're planning; and then conservatively predict sales for the coming year.

The difference between selling online and selling in a store, however, is that changes, both good and bad, often occur much faster online than in the real world. So an e-business should react much more quickly (and often more creatively) than an offline operation.

Also, e-business allows for more accurate predictions because selling online enables an operator to gather much more information on customers. This information – such as their preferences, how they found you, their buying range in terms of dollars, motivations, and point in the buying process – can then be better used to perfect the selling process.

Lastly, with e-business, new sales and marketing methods can be continually introduced, tested quickly and expanded if successful, or dumped if they are not.

All these factors could skew your forecasts somewhat, so you might want to consider them when making your predictions.