If everybody practiced this, there would be no unsolicited advice. That would be good. Unsolicited advice robs its recipients of the power of learning something for themselves, which is the only true learning. Those who welcome unsolicited advice are afraid of imagined evils. Let there be no unsolicited advice. Banish it from your repository of tools.
Say only what you are directed to say, what carries no ulterior motive since it seems not to come from you. Cultivate sacred space within yourself, so that you hear more.
They have to ask. Your example is stronger than any words. It is not necessary to editorialize on your example; just do. If you wish your example to be most powerful, know that talk about it chips away its power. Your silent, conscious example is your most powerful tool for good.
Example, the most powerful tool
This is the act of believing in free will. Nothing can exist without free will. If they did not choose it for themselves, it does not count. This means giving up all manipulations of other people. Give up trying to get anyone to do anything, no matter how much it is for his or her own good. They have to choose. (We are talking about grown adults here, not children who still need help navigating the physical world.)
Giving up manipulations is natural when you give up attachment to outcomes. Give up all pushing and pulling. Give up trying to arrange reality.
They have to ask. This works in any situation. Should you give your opinion? They have to ask. Should you offer them help? They have to ask. Would you give them directions? They have to ask. Would you tell them how you would do it? They have to ask. Do they want to know a better way? They have to ask.
Be silent and know. Create sacred space within, so that the answers have a place to come.
Wait until they ask