A tattoo that is bright red (even in part) you camouflage with 408. The other colours and lines of a tattoo you camouflage with IV5.
Take the Camouflage Make-up Pure out with a clean spatula and work from the spatula, or directly from the stick. Rubbing it with your fingertip will make it softer and easier to handle.
Apply the camouflage with a brush (or a latex sponge for larger areas) and blend the camouflage using a tip of the latex sponge.