Measure the mixture out properly and use exactly the same cake tins. When I made DD's cake, I used tins that were the same size, but not exactly the same (brought at different times) so the cakes were a slightly different shape and you could see they were uneven when she cut it. It wasn't a huge disaster, but I could tell!
It isn't difficult to actually make, it just takes time, especially when you only have two cake tins to make 7 cakes with! I used a plain old butter icing and although it was a little yellow-ish, it still looked pretty good!