First and foremost, it is important in my opinion to listen in such a way that others love to speak to you.
Second, if someone ask for your opinion, tell the truth, not what they like to hear.
Then you become a good listener. I think it's wrong to just talk nice. My experience has been that the truth hurts, but most know the truth and just do not want it true. if it speaks another person, it becomes real. As a listener, you also have to learn to hear the things the other one does not say. Watching the gestures and facial expressions is very important.

My favorite thing is when people remember little things I told them. Like, you really listened to me?

a very nice question ^^