Use the Smallest Piping Tips Available

• Piping tips for icing bags are available in many sizes. For piping petit four cakes, use the smallest tip possible. Use a coupler (a base and ring that attach to any piping bag) to switch different tip sizes without having to fill a new icing bag. Make sure the piping tip is clean and dry before you attach it to your icing bag.
  
  

Using Toothpicks

• Toothpicks are an excellent and cheap tool you can use for applying miniature decorations to your petits fours, such as dragees (small silver-colored balls), sugar flowers or sprinkles. Dip a new, clean toothpick into a very small amount of quick-setting icing in a neutral color, such as white royal icing, which is made with meringue powder and confectioner's sugar. Dab the icing onto the desired location on the petit four and quickly apply your cake decoration of choice, applying light pressure to gently cement the dragee or sprinkle in place. Toothpicks can also be used to quickly remedy piping errors from often-imprecise piping bags.
  
  

Gel Icing Squeeze Tubes

• For piping petits fours, using a large icing bag can be unwieldy. Look instead for more manageable squeeze tubes of gel icing, available in most grocery stores in a variety of colors. The gel icing is made to squeeze out in a neat, tubular shape, which is ideal for piping line-based designs and swirls onto your petits fours.
  
  

Use a Smooth Base

• Artists begin working on a blank canvas, and so should you, as a cake decorator. Make your work surface as smooth and even as possible. Use a quick-pour fondant icing to get a perfectly frosted petit four with minimal effort. Fondant icing can be molded around the shape of any petit four to create a smooth exterior that will showcase your piping beautifully. Plus, it's easier to remove piping mistakes from fondant than from bare cake, which can crumble under the slightest pressure.