Hey, I think I can help. I didn't read all the replies so forgive me if I'm reiterrating anything anyone else said. But harmonics is my specialty and I've only been playing a month! It's the ONLY thing I can do well.

The trick is .... BARELY touch the string with your left finger and pluck hard with your right finger. It's hard to remember to touch lightly because with our left hand we have to push the strings down so hard you know? Remember, light touch.... barely touch it and see yourself fly!