Cakes take anywhere from one day to a whole week to make. Fondant lasts up to 1-2 months at room temp as long as it is wrapped with everyone's biggest archenemy - plastic wrap. Seriously does this stuff cling to anything else but itself? I'm rooting for you here. All the same and back to the point, doing your fondant decorations in advance is a nice way to get started on your cake early.
I make sure everyone around me has enough wine until I start to look good.
Oh I just sit around doing my own thing and they come to me like magic. No silly! I do like everyone else and obsess over instagram and pinterest until I formulate an idea.
The easiest one is going to blow your mind because it is also one of the coolest looking ones. I recommend starting with the Reece's Pieces Pour cake. My grandchildren made the cake in one of my cake baking classes for kids. I promise it is easier than it looks!
The most common mistake I see people make is not following the directions. Seriously people don't get over confident and think you're better than the recipe. While certainly there are times you see fit to make changes to recipes you're already experienced with, stick to the program when making a recipe for the first time. By harmless changes I mean you can add vanilla extract to cake mix ingredients to give it more of a homemade taste. I don't mean subbing out eggs for applesauce or other crazy little acts of destruction.