A good business plan is always the best way to go when starting any kind of business. Without one, businesses tend to fail, however, I don't think HostGator having 3 servers in a basement had a business plan. It really just depends on the business and technical skill of the founder.
My suggestion for starting a hosting company would be to go with reseller hosting if you don't have much experience or don't have all the time in the world to devote to your customers. Reseller hosting is just the easiest option to start out, given that you are provided all the relevant tools to start-up.