A basic tool to help you with forecasting is previous sales. You should see periods when sales were up and when they were down. Sometimes the peaks correspond to marketing activity like a trade show or direct mail. Other times ups and downs are caused by the seasons, especially in retail. Then there are industry specific peaks, like August for Federal Government customers.

If you have no history, research your competitors. If they are a publically traded company their performance can be found in a number of resource locations.

Finally, the goal in forcasting is to be exactly on target. Sounds obvious? Be careful. To over forecast will make your boss happy untill you fall short of goal and have excess inventory. To underforecast is even worse. You won't be able to meet customer demand.

Good luck.