Form joint ventures and partnerships to expand  Just because these entrepreneurs prefer to run their businesses as solo operations, they don't always go it alone when it comes to growing their firms. In fact, many have found that teaming up with other businesses and organizations is one of the best ways to prosper.  Ask Robert Smith, who runs the public relations firm Robert Smith & Associates in Loves Park, Ill., and expects $1.4 million in 2014. He is constantly on the lookout for opportunities to partner with other organizations and businesses. For instance, early in running his business, he made arrangements with a county that handed out a packet of useful information to owners of businesses who'd filed paperwork such as a "Doing Business As" registration to provide tips on public relations—attributed to his firm. "It came with an implied endorsement," he said. In another such venture, he set up a kiosk at a local printer's business. Typically, he'll pay a commission to other businesses that refer new clients.  He's not alone in taking this approach. HRN's Cohen has found her webmaster so valuable in expanding her reach that when she sells a new business opportunity, she pays the webmaster a percentage of the business. If Cohen refers work to the webmaster from her own client base, she in turn receives a commission from the webmaster.  Cohen also wins customers due to an active network of Realtors, decorators and owners of home-improvement businesses who refer customers to her. "If that turns into a job, I give them a percentage of my commission as a referral commission," she said.  —Elaine Pofeldt, Special to CNBC.com
More elite solo entrepreneurs are scaling up and building businesses with $1 million in sales. Here's an insider's look at how they getting rich.