Dry flies on still water

[Runewolf1973]

How do you fish dry flies on perfectly still water like on a pond? Do you just let the fly float with no movement/drag whatsoever, or do you twitch the rod, or slowly retreive the fly to give it some movement like a bug fluttering on the water? Conversely, on water with some wind and small riffles, do you just let the riffles carry the dry fly away naturally with no drag? I feel as though the fish are seeing my leader or some unnatural movement or something and getting spooked.

Thanks,
Randy