Take a look at Paris Cutler's expert tips for using royal icing.
Making Royal Icing
You can make your royal icing from scratch or buy instant royal icing which is a good substitute.
Before piping with royal icing, it is essential to have it at the correct consistency, not too runny and not to thick as it will keep blocking the piping tip and drive you crazy!
If you wish to colour your royal icing, add icing colour paste in very small quantities and mix the royal icing and colour together using a palette knife. We do this on the bench but you may want to try a board or plate. You can use liquid or gel icing colour and if you use the colour paste use a tooth pick to add the colour, as a little will go a long way.
Royal Rough Icing
This icing has a meringue-like texture, and is a very different look to the super smooth fondant. For Royal Rough icing to look shiny and sumptuous, yet still able to set and hold its shape, add glycerine. This will also stop the Royal Rough icing from setting too hard. This helps when the lucky couple is cutting into the cake to ensure dried icing doesn’t crack everywhere. Too easy!