I believe the trick is to know your customer, and really understand their process. I don't think there is any value in giving away introductory DNotes because there's no reason to believe that less than $5USD is a deterrent. I would consider the learning curve, and the time taken to get through enough of the learning curve to be confident, is the biggest deterrent for new investors.

With this in mind I would suggest a highly structured introduction with a focus on not wasting the customer's time. We've seen software 'wizards' used for more than a decade to step people through a complex process. This wizard should not stop at the investment point, but go all the way through to a withdrawal.

For example, the customer clicks the "I'm interested, but don't know enough to be confident investing" button to get into the wizard. They have summaries of the important points with hover text over industry terms and on-screen or side panel pop-ups for more detailed information. By the end of it, they use a well known and familiar payment gateway like Paypal to buy $5 worth of DNotes. Then they get an email when their $5 DNotes quantity is worth $6. This email encourages them to cash in 1$ worth of DNotes so that they get money back in their hand and see the whole process end to end.

This final 'money back out' stage could be incredibly powerful in enabling them to recognise the full power of DNotes as a financial tool. 

Then, once this has been developed, set up in a public space, hire a stall in the shopping centre, and pay some people $5 to invest $5 in DNotes. Watch over their shoulder and note down all of their question and complaints. Re-build your wizard based on what you learn and do it all again.

It is incredibly hard for someone capable of putting something like DNotes together to meaningfully relate to the thoughts and feeling of an off the street customer. The knowledge gap between the developer and the user is so incredibly vast. Experiencing this gap is the only way to bridge it.