Below are the most common cake decorating mistakes and easy ways to rectify them. 

Anyone who has ever frosted a cake knows there are times when the icing will pull apart the top of the cake and cake crumbs get well into the frosting. To stop this from occurring, you should start with a crumb coat. This is the same icing that you are using to frost the cake, but it has been thinned down a bit. That way you will cover any part of the cake that might crumble with a thin layer of icing, and it will give you a base over which you will put a regular coat of icing. Take care that you do not make the icing too thin. It should be thinned down just enough to cover the cake without tearing it and picking up crumbs.
    
After you apply the crumb coat to the cake, you need to let it set for about 2 hours or more before you apply the rest of the icing. In fact, it should rest in the refrigerator and can be kept there overnight before you need to add more icing. It is okay if you see crumbs in the crumb coat, they will be stuck in this first layer of icing and will not affect the next layer of icing. The cold will set the icing and it will be a cinch to the ice after that. 

There can be a problem with fillings spilling out the sides of the cake. There are ways to stop this from happening when your cake decorating involves a filled middle. 

1. Bake your cake the day before you are planning to fill it. This will make the cake firmer and will give it time to settle. A freshly baked cake will be unstable and will not hold fillings as well as when they are settled.

2. You can also use icing to make a dam to stop the filling from spilling out. Once the dam has been made, you can frost the whole cake with a crumb coating. The cake should be set in the refrigerator for 2 to 3 hours, or overnight, this will firm up the icing and will keep the filling from oozing out the sides. The dams made of icing will firm up and keep the filling in.

If you are a busy person and don't have time to bake and decorate a cake all at once, you can bake the cake and freeze it until you need to decorate it. A cake can be kept in the freezer for a couple of weeks before it needs to be used. You must prepare the cake for freezing by wrapping three layers of strong cling wrap around the cake, followed by one layer of aluminum foil just prior to freezing. If you do not follow this procedure, your cake will dry out and crumble. You will also need to make sure the cake is completely thawed before attempting to ice it.

You will need to allow the cake to defrost slowly, at room temperature, for one or two days until it has defrosted. Icing a cake before it has thawed will make the icing sweat and become mushy, this will ruin your cake decorating, and all your hard work will be for nothing.