As important as it is that you make your dessert look beautiful, ultimately it is food, and someone will stab it with a fork and eat it.  With that in mind, construct your dessert wisely. 

More sturdy layers should go on the bottom.  Lighter, creamy layers should go on top.  If you want a crispy layer in the midst of the creaminess, make sure it is either a)a very thin sheet or b)broken up into crumbles so it doesn't press down on the creamy layer causing it to guish (pronounced gwish) all over the place. 

Use common sense.  Oh, and have you ever wondered how those pastry chefs who compete on the National and World levels build cakes with 8 perfect layers of vastly different components?   Molds and freezers, my friends.  Layers stack much better when they're frozen.

Here are some pictures of some layered desserts. See if you can figure out which ones will work and which ones won't. I will refrain from commenting. Unless you mouseover each picture...