The first time you give uninvited advice you will most likely be ignored.
The second time you give uninvited advice the person is likely to be annoyed.
The third time you give uninvited advice the person is likely to push you out of their life.
When people give too much advice they lose the privilege to speak into that person's life. This can happen between parents and adult children, friends or any other relationship.
The good news is saying nothing at all often results in people inviting you to give advice. If you meet people with love and compassion, and a good listening ear they are likely to open up and seek advice. At that point they just gave you permission to speak into their lives. Then the advice you give has a much more powerful effect on their life and the relationship is not harmed.
The biggest point to understand is that a person must feel loved, accepted, and listened to before you give any advice.
During the listening period you do not have to condone or encourage problem behavior but it is not time to tell them how to change it. If you want them to hear you, you must listen first.
For more on listening skills read my article on how to be a good listener. http://www.revitalizecounselingservices.com/2012/03/how-to-be-good-listener.html