Mix the whole mix white, separate into smaller containers for all the colours you wish to mix. Then add the colouring to the smaller quantity and mix. You will automatically have less white that must be coloured and you will also use less colouring. Let it rest for 5 minutes and you will see the colour will be brighter add more colouring should you need the colour to be brighter or darker. Should you wish to colour a huge amount of icing the same colour such as red, follow the same steps as above and then put all together in one bowl again and mix to get one solid colour. You will be surprised to see how little colouring you use. The exact rule can be followed when colouring white fondant. The smaller quantity you colour the less colouring you will use, and then put all small pieces together to mix it to one solid colour.