This example shows a simple forecast of web-related sales by month, with cost of sales by month as well. Add up 12 months to get the totals for the year. The educated guessing might be hard, but the math is simple, and the spreadsheet work is simple. The math of the sales forecast is very simple. The content takes work, but not the design of the table. It's built on common sense and reasonable guesses, without statistical analysis, mathematical techniques, or any past data.
In the example below, columns are vertical, rows are horizontal. Each line of sales occupies a row, and months and years occupy columns. The total sales row sums the individual sales rows. The annual sales column sums the months for each row, including the total rows.


Sample from Web Strategy Pro.
The source spreadsheet hides the monthly columns for April through October for the purpose of illustration, so you can see the annual total without scrolling. Those other months are there, even if they don't show.
The forecasting depends on how well you know your business and your market. The sales forecasting starts when the research is done. The mechanics of sales forecasting are relatively simple. Ultimately a forecast is a guess, but we want it to be an educated guess.
Break your sales down into manageable parts, and then forecast the parts. Guess your sales by line of sales, month by month, and add up the sales lines and add up the months. Take another look at the illustration above and imagine how you would build a forecast for your own business.
Summary
A sales forecast is hard for many people because they are unsure of how to forecast. Don’t worry, if you know your business, you can give an educated guess of future sales. Remember, one thing harder than forecasting is running a business without a forecast.