Decide on the cake you would like to bake. The Madeira sponge cake is better for larger cakes as it is firmer than a Victoria sponge cake. Sponge or Madeira cakes can be baked a day or two before you decorate them, fruit cakes can be made months in advance before decorating them.
Turn the cake out on a wire rack to cool when it is through baking. Cover a bread board or a strong piece of cardboard with foil to present the cake on. If the cake rises a little too much on the center slice it off to level it out once it has cooled. Sandwich the tops of the cake together so you can have a smooth surface to ice.
Place the cake in the freezer for one to two hours before icing to prevent crumbling.Fill the icing piping's bag with the icing sugar and use it to make different sized nozzle attachments like drawing roses or writing a name. The icing tube makes it easier to write or design what you like. Use a snap-lock plastic bag in case you do not require elaborate designs. Cut a hole in the corner of the bag, fill it with icing and use it to make your designs.
Choose the preferred theme for the kid's birthday cake. Use a cake stencil to make designs or writings when decorating. Sprinkle colored sugar or dry icing through the stencil to make the design or writing. Use white icing powder on a chocolate cake to stencil and cocoa powder on light colored icing.
Refer to a picture book or toys for a design idea on the toppings to use on the cake. Use small plastic toys that interest the child as cake toppers; an example is a miniature train on the icing.