You've written a solid business plan, secured your funding, and jumped through all the legal hoops. You're ready to start doing business, right? Not so fast. A great startup idea won't do you any good if people don't know about it. While there's still a lot of value in word-of-mouth advertising, you're going to need to do more than just tell your social circles that you're starting a business. Before you start selling your product or service, you need to build up your brand and get a following of people ready to jump when you open your literal or figurative doors for business.