Have all component parts and equipment ready before beginning to assemble the cake.
Make sure that the cake is completely cool before you attempt to slice it into thin layers. Prepare the cake a day or two in advance and wrap and chill it. If the cake is freshly baked, it will shred badly when sliced.
Use a long, sharp, serrated knife for slicing a cake into thin layers. Even a professional pastry chef can’t slice a cake into even layers with a short, dull knife. Holding the knife blade parallel to the work surface, about ⅓ or ¼ inch down from the top of the cake (depending on how many layers are to be cut) mark a line with the blade of the knife all around the side of the cake. Continue pressing the knife into this initial line, revolving the cake against the knife until you cut all the way through.
Assemble the cake on a cardboard disk of the same diameter as the pan in which the cake was baked. You can buy boards from a friendly bakery or at a kitchenware or cake-decorating store. Paper wholesalers carry them in quantity, if you wish to invest and split a case with friends. Although I admit that the cardboard gives a slightly commercial look to a finished cake, the convenience and ease of handling far outweigh any aesthetic reservations.
Use a thin-bladed metal spatula, preferably an offset one, for finishing the outside of a cake. A bulkier tool will prevent you from spreading the outside coating flat and straight.