As an example, let's say your current average number of transactions per month per customer is 3ǌ. Which says on average each customer does business with you 3 times each month. You could calculate how much more profit you would get if you could increase it to 3Ǒ. And I can tell you that would probably be enough to meet your plan. And if that did generate enough profit, all you would have to do is maintain everything else; sales, expenses, labor, average dollar sale, etc, and then just figure out how you could increase your transactions from 3ǌ to 3Ǒ. Maybe it could be with some type of promotion that would get customers to come in more often.
At this point, you may be tempted to skip writing a business plan altogether, viewing it as an unnecessary exercise in jumping_through_the_hoops, suggested by some old business professor who probably never held down a "real" job anyway. Maybe it's okay as an assignment for an MBA class, but it would be just too confining and irrelevant for today's fast_paced business environment. Anyway, you're ready! You've thought about this business venture for a long time and talked it over with friends and everybody agrees it's a great idea. Best to strike while the iron is hot!