C-Man, here is a bunch of questions you should ask yourself:
What cards do you want to run?
What colors are they?
Is there any lands out there that combo directly with what I'm trying to do?
Am I wearing panties?
How many of each color of cards am I running?
How many cards are in my deck?
And then you should come across some answers about what your needs are for special land types. But dont look at me for those answers or suggestions, because not only have I not played in like 8 years, but I also dont know what you are running yet. =) Hope this helps!
edit**As for snow-covered lands, back, back, back in the old days of Ice
Age, there were creatures with Snow-Covered (insert land)walk, and maybe other Snow-Covered abilities?