Forecasting is not an exact science but it is important in order to stay in control of your business. First up, focus on expenses. Think about how much it will cost to run your business, including paying staff, rent for premises and the cost of marketing, technology, and other bills. Leave some leeway for unexpected expenses so that you will have some money up your sleeve just in case. When it comes to revenue, try to forecast conservatively and based on historical data as much as possible. You can always revisit your forecasts if you find you are exceeding them.