The problem is, there are no simple “right” answers for most Web design questions (at least not for the important ones). What works is good, integrated design that fills a need – carefully thought out, well executed, and tested.
And there’s only one way to answer that kind of question: testing. You have to use the collective skill experience, creativity, and common sense of the team to build some version of the thing (even a crude version), then watch ordinary people carefully as they try to figure out what it is and to use it.
There is no substitute for it.