It should be clear that you only have 1 chance to make a first impression.  So, any private investor is going to judge you on what you say, and how well organized you are.  Because an investor is going to think that the same attitude with which you approach your presentation will be the way you handle his money.  So, you should have at least a clear business plan in your head and a written summary of it that you can share with your potential private lenders if they are interested.  And if they are interested they are eventually going to want to see a complete business plan before they invest.