When it comes to buying a business, a good business plan is crucial. It's an invaluable guide to listing your objectives and aims in detail. It's a good source for information and analysis of your aims, targets, customers and prospects. All in all, it's a great resource to refer back to time and time again. By setting up the business plan, you will have a better chance of success because you have listed everything down in your head on paper.
A lot of resources nowadays provide ready-made plans for specific businesses and whilst this is handy, most business owners will recommend that you write the plan yourself. This is because writing a plan for your business actually forces you to focus on what you want from your business and how to achieve your goals. When looking back on your initial plan for reference, you shouldn't necessarily assume that your initial assumptions and predictions will be correct, they are just that: predictions. You should be able to go back to your plan on a regular basis and view it and change it to relate to the actual current situation.