Here in North America people often own several kilts in a variety of tartans, where as in Scotland people usually one only one kilt, and 99% of the time it is in their family tartan. The result of this is that North Americans often obsess about matching colours with the colours which predominate in their kilts.

On the other hand, in Scotland, nobody really worries about such things, so in that regard a kilt really is very much like a pair of khaki trousers (although less prone to show that bit of haggis that fell into your lap at lunch!).

I think if you check out the "One Kilt--Ten Looks" thread at the top of the General Kilt Talk forum you'll get a pretty good idea of how to wear the kilt in virtually every situation.