The most leads come where marketing promotion and content are set up so the visitor flows naturally from one to the other.
They start investigating or discovering free content, then from links in the content or below/around the sidebars or a popup lightbox they click through to other material. And then an explicit sales message is put in front of them that they activate.

The way to plan and structure your content is to first plan your product sales hierarchy (what they buy first, second etc) and then align the content which will persuade a visitor to buy each to work in concert stepping them up naturally from a browse to a first purchase, return for a second purchase etc.

I suggest you start with a planning session to map out your business products and the content you've already got. Then put these into a process so new content, new social sites and new products can be added over time using the same structure.

If this sounds a bit confusing, give me a call and let's help you out.