Working with swatches.
Using the swatches palette in Illustrator is very simple to do and can make working with specific colours a lot easier. You can add swatches using the palette, meaning that the colour will be easy to find when you need to use the exact same colour again. This is also useful when printing, as you can lower the opacity of the ink colour, however at a printers it will still cost the same amount to produce, as it would still be the same ink colour. It also means that when you change one specific colour, all of the colours that are the same in the document will change too. It's very handy and saves a lot of time. You can save and open up swatches so that you can create multiple designs, for example posters, using the exact same colour scheme.