When I do a 3-D cake on top of another cake, is it best to secure it on top of the cake first, and then decorate it? Or decorate most of it first, and then place it on top of the cake and secure it? Thanks!

I find it easier to go ahead and decorate the character cake, which is sitting in its own cake board (cut to the shape of the character cake) and then put it on top of the other decorated cake. Once it's on top, then just do the border around the character cake. You might also want to put dowels under it, depending on the weight!