By letting professional sales staffs do the closing.
The systems I use -- including the one displayed on my IBO profile page -- employ them as part of the program.
I'll do the marketing and turn prospects over to them. If they make a sale, then I'll be right there with the follow-up. If a prospect has a question during the sales process and wants to ask me instead of a sales person, I'll respond immediately.
My experience is that many people want to run an online business, but not so many of them are good at sales. No problem. Leave it to those who are. That's the beauty of a full-service system.