I've seen pictures with fondant covered cakes, and after "settling" the fondant cracks or messes up. What causes this? Is the fondant too thin/thick? Is the cake too moist? How can you avoid it?

Put a tile on top of your cake after crumbcoating and let it sit overnight. That should force your cake to do all the settling it needs to prior to covering it with fondant or buttercream.

I heard this tip 1000 times before I ever tried it - it solves SO many problems with fondant or buttercream. HTH