Terrible 1's!

We have hit a rough patch with Harleigh.  She is 17 months and apparently is the Queen of the World (or so she thinks)!  She doesn't like when she's told "no" or doesn't get her way.  She will throw a fit- the works- tears, screaming, and laying down on the floor, as if her world has officially come to an end.  It's hard not to laugh, at how dramatic our child is (we all know she gets this characteristic from her daddy:))!  We need some suggestions on breaking this child!! We're hoping we won't have to go through this when she's 2 again!!