Most recipes call for the Icing to be put onto a cold cake. Don't get in a hurry, make sure it's cooled all the way to down to room temperature or the Top layer(s) may just slide off of the bottom layer(s). Once, I thought I'd be smart and cool the layers down quick in the refrigerator, bad idea, the outside cooled off but the inside didn't. When I began icing the cake, the warm inside heated the outside back up and the second layer went bye-bye.
If you don't have AC and it's a hot day, you may have a problem with the layers slipping on a completely cooled cake. To keep this from happening, take some wooden skewers cut to a little longer than the cake is high, and stick three of four of them down through the cake to hold it steady. When time comes to serve the cake, remove them and smooth the icing and your guests will never know that they were there.
No matter how good the cake is, most people (especially the kids) like the icing better, so give them more of it. Take each layer, then using a bread knife, slice each of them into two layers. That gives you twice the layers so make twice the amount of icing and you'll be the favorite baker in the neighborhood.