Credibility is key in both attracting and closing sales. No matter what you're selling - you are the product, so be a professional marketer. Everything that you send, every relationship you conduct, and every way that you market yourself will dictate either success or failure in the future.
You have to be able to consistently propel new customers, and find new ways to make marketing work for your current clients. You accomplish this with integrity, honesty, and a genuine desire to help others succeed. You can't run a business on charisma or a great database alone.
Want to build passive, residual income? Then build your marketing permanently. This means you've got to associate with and use only credible suppliers, vendors and partnerships. Execute well, and learn to convert prospects into sales automatically.