If you develop a good Profit & Loss Statement for your existing business for the current year or for the first year of your proposed business, you can use this data to actually project how much sales you would need to yield the income you want and the profit margin you want. You can plan ahead as far as you want. Sound impossible? It's actually pretty simple and can be pretty accurate plan.
Developing Planning Modules: Compartmentalizing your plan by developing planning modules or "chunks" allows you to attack the plan in parts, yet still maintain a cohesive plan. I have found that developing an annual plan made up of quarterly targets _ thus becoming a rolling quarterly forecast financial model _ allows for a cohesive structure along with the nimbleness to react to market conditions. At the end of each quarter, a true_up process to align results to annual targets needs to be re_forecast and adjustments made.