Ask HN: How do you discover project requirements and transcribe them to specs?

As a team of web developers, we having trouble getting robust sets of specifications together for our projects. What we do put together is normally half-baked and incomplete, not addressing all of the issues or features. This is something we want to change as we realise how important they are contractually as well as functionally (for testing etc.)<p>Some of these projects we are ourselves closely tied with, so we actually have all the information. Others we need to get that information from the clients. The problem is trying to get it all down on paper in a useful format and structure.<p>How to you manage requirement gathering and spec writing?