When you begin to use your website and measurement tools for ROI, you have yet another bridge to cross. You need to build trust within the people who use your site and/or respond to your various marketing efforts. The first step in building trust is to be accessible. If your site is easily navigable, even the timid users will be able to dig in and find the information they seek. Make all the necessary information easy to access on your website, and you should see a corresponding increase in customer response.
Next, you have to be authentic and transparent as an organization. Customers have to be able to rely on you to deliver those goods and services as promised. And those good and services need to be just as good, or better, than they expected. In addition, you need to be aware every day of how relevant your marketing and sales efforts are to your customers. It's a cycle: The more value you provide to them, the more "likable" you will be. And the more likeable, again, the more trustworthy. Trust is an important emotion in the buying equation, and trust will greatly extend your ability to generate more ROI.