Great input from John, Mads and Andria. Being in the outsourced sales business, I can say definitively that lack of planning and process clarity will have you struggling with either in-house or contracted structure.
Oftentimes, the CEO/Founder of a company is naturally the strongest salesperson the company has or will have. It may be more effective to find an operations/account management person to handle some of the onboarding duties while you maintain a focus on the selling.
Sales is a process that warrants documentation and management, just like all of the other processes in your company. If you understand how the sales process works effectively for your business, manage the resources that you assign to the process, and, as Mads points out, you know what your results should be, hiring direct or outsourcing can be very effective.