Where you build your quinzee is pretty important. If we had needed quinzee to sleep in, we would have found a nice sheltered spot, on level land. We opted to build ours on a lake instead. Now, frozen ice conducts heat much better than frozen ground, so sleeping on a lake will draw your body heat away much faster. That really sucks. Not a good choice for over-night campouts, but were just building this one just for fun, so it wasn't an issue.
Where ever you choose to build yours, start by digging out all the snow from the area that your quinzee will sit. Then shovel it all right back. Moving the snow like this will cause it to settle out and give your quinzee a good solid base.