The first advice works because by being candid and genuine, you are willing to make yourself vulnerable, and it means implicitly that you the trust the person y

The first advice works because by being candid and genuine, you are willing to make yourself vulnerable, and it means implicitly that you the trust the person you are talking to. And it will be easier for the other person to open up as well. It also works in professional settings. It is better to work with people who are willing to say upfront "I don't know", rather than keeping quiet and ending up doing a bad job, because they were afraid to look weak. So if you want someone to confide something, tell them one of your secret first. (But do not plan it in a Machiavellian way or it will surely backfire, the key is to stay genuine and really care at all time.)