Well. First of all, make sure your pans are both the same size. I'm just going out on a limb here, but it might make things more difficult if you use an 8 inch square pan and a 9 inch round pan.
Also, two things about coloring your cake: Yellow cake does not dye well, and make sure to remember to color both cakes.
Thankfully, I have a tester child with which to practice my creativeness, and she's still too young to remember the lopsided, poorly iced, poorly decorated cakes her Gigi and I made.
Also being tested on Olivia: My observation skills. On Wednesday, when I started vacuuming the rug, she was sitting on the kitchen floor with a closed makeup bag. When I finished vacuuming, I found her outside with one of my makeup brushes, sitting in a chair
Something else I need to work on: her hair. It's always in her face. It took me about 25 years to figure out how to make my own hair semi-presentable. I feel the need to get better at handling hair for this poor child. Last night, we practiced pig tails. They weren't perfect, but they were damn cute. And so were her glow in the dark Halloween PJs.