A lot of those mistakes (most of them, in fact) are the result of poor planning. Bad location, a marginal niche, having no specific user in mind, raising too much or too little money-all of these issues can be prevented or at least mitigated with good planning.
Creating your business plan is more than just getting your ideas down on paper for potential funders to see. It’s an exploratory process in which you can evaluate your options, test your assumptions about your idea, and even discover new opportunities. It might even lead you to kill off aspects of your business before investing too much time or money in them.