Bryan from Entrepid here. We disagree with the advice of hiring a head of sales as your first sales hire. You are better off finding a someone with 3-6 years of experience to be the first hire as an IC. This hire (and maybe a few others) will help you grow the company to a point where you can attract a badass VP of sales / head of sales
In our experience, the founder should close the first 3-10 enterprise deals on their own. When you chose to outsource, you may close some deals, but you lose out on the early customer product feedback.
The relationships with your early customers are key. You need to make your early customers your biggest fans to show how your product changed their business through references and/or mini-case studies.
Bryan from Entrepid Partners here... we find that highly targetted, outbound cold emails are actually the best place to start prospecting.
In our experience, if you do the extra work to personalize the email and focus in on why your product/service is relevant to the buyer's pain points, we've seen response rates as high as 30% with the majority of those replies turning into an intro call with the buyer.