Show alert for users with 0% (or low) acceptance rate
I've read suggestions about preventing users from asking questions when they have a low accept rate. And I do agree that it will not help.
However, what about an notification (the orange top div) that shows a message like "We suggest that you start accepting answers, read more here". The link goes to a page describing the accept process in a very detailed way with lots of screenshots.
The nag notification should be shown now and then.
Might even encourage those who doesn't accept answers even though they know how to.