Just what HanahDJ, HsannhDJA,HannnahDJ, HannahDJA said!!!
GOD I can't spell your name right, sorry :/
Just kidding XD
You can't just make white planes and call it a snow cave!
You must instead make another cave since it might not work out to make a snow cave, and no you don't really need to tell something to help you out with the map detailing or if you want.
The best way is to open your imagination!
That's what happened to me before, I was just doing empty rooms that made no sense, but after playing other custom stories and seeing all the maps and stuff, then I opened my own imagination and made my own maps! to make good looking levels just like mine or anybody else, you mostly want to use decals, and lots of furniture, but remember the level must make sense. and yes slow down and be creative, don't be hyped and be fast! I know that feeling, but if you want to make well made maps, you must be slow and creative, got that?
These are pictures from my levels, the ones that you see are just rooms from different levels!
http://www.mediafire.com/download/4q685d...images.zip
my level images might help you out into map detailing, I hope