Go up somewhere high, and just like sit there.. bring something that calms you, like music r something and just chill... just tell your self that it's no big deal, and everything is going to be ok :)
Get some friends to accompany you when you get somewhere high. Find a place where its kind of boxed in so you feel secure that always seems to help me :)
I tried this out going out to highest point of a building, but it didn't come of any help to me