Baby steps, the brown paper bag for hyperventillation(if that comes into play in your case), Never thought it did anything but inhaling some of that carbon dioxide calms you. I keep a brown paper bag in my car for driving anxiety.
Then there's always my approach, Alcohol/Benzo's but if you're not on 'em I wouldnt suggest 'em. Or diphenhydramine(stuff in benadryl),Melatonin, some of that herbal stuff if you're looking for some kinda drug that's virtually non habbit forming and safe(used in moderation).