I teach that you should seek to learn from competitors; obviously never copy another business's idea or what they are doing, but you can absolutely learn from their mistakes or see what they are doing and discover ways to improve it. All of that analysis belongs in your business plan: make sure you have your competitors under the microscope and make sure that is a solid chunk of your plan. That is some of the best research and information you will gather about what will make your business successful in future.
I don't know of better way than to let your business give you what you want for your lifestyle. Whether it's a sample business plan for a small business or one where your business gives you a plan, it should tell you what is needed to take you where you want to go and when and how you can get there and it should be in clear simple terms, supported with all the specifics. So using a sample business plan for a small business is just one of many ways to make a business plan but frankly I think designing one that will have your business give you exactly what you want is by far the best way.