When covering a cake with fondant, what do you do? Do you just place it on top of the freshly iced cake, or let the buttercream crust, or attach it using another method?

Thanks!

You just put it on the freshly iced cake, since you need the icing to "glue" the fondant to the cake. Use only the thinnest possible layer of frosting, or your fondant will bubble out from the sides of the cake. Once you have it on there, smooth it out with your hands to cover the cake without wrinkles, then trim at the bottom. It takes a little practice, but the effect is really cool. I just used Satinice fondant for the first time today, and I love the stuff.