It's like planning backwards. 1. Determine what you want in life 2. Figure out what your business would need to do to give you that life. 3. Figure out how long it would take you to reach it. 4. Figure out how big of a market it would take each of the years you're planning for. 5. Then see if that market is big enough. Isn't this a much better way to go about planning your business? Shouldn't your business be designed to give you want you want instead of you working yourself to death just hoping for the best?
So, although a detailed business plan may not be required for an online business, I am going to include it here so you can at least look at and consider each section and determine yourself if it applies to your business.