Makeup is all about colours, colours and colours - in their different hues and intensity.  Since I have come to realise that colour combination and colour management is very important in makeup application and understanding of its techniques, then I have chosen to write again. Enjoy!
Primary colours which are basic colours that cannot be obtained by mixture of other colours. They are Red, Blue and Yellow.
Then we have Secondary colours which are obtained by the mixture of two primary colours but are also strong colours; Orange - gotten from yellow and red, Violet - from red and blue and Green - from yellow and blue.
Now all these colours have their soft pastels which are also known as earth tones or off tones
-      Off tones of Red: pink, burgundy, rose, fuchsia, tan, bronze, copper, ruby etc.
-      Off tones of Orange: caramel, coral, peach, salmon, apricot etc.
-      Off tones of Violet: lavender, purple, lilac, magenta, mauve, etc.
-      Off tones of Green: jade, khaki sage, aqua, mint, avocado, teal, army green, sea green, olive, lemon green etc.
-      Off tones of Blue: powder blue, aqua, steel, baby blue, pewter, turquoise, royal blue, teal, sapphire etc.
Having known all these, there are rules that guide the use of these colours when it comes to makeup, in order to achieve a beautiful makeup outlook. (Though since makeup is about expression, one can still very much go against these rules especially for runway, fashion or photography makeup, but outside these it is advised that a makeup artist should stick to the rules).

Law of colour compatibility
-      All earth tones are compatible with all earth tones. For example, you can have pink eyes hadows and pink lips.

-      All earth tones are compatible with a primary colour. For instance, you can have a mixture of gold and green eyeshadows and peach lips, orange lips or even red lips.

-      But not all primary colours are compatible with each other. For example, you can’t have blue eyeshadows and red lips, or green eyeshadows and red lips, they are both strong colours and that means the eyes and lips are calling for attention at the same time which shouldn’t be.

When your clients do not know their likes and dislikes in terms of makeup tones of eye shadows, lipsticks, blush etc., then stay as colour compatible as you can. Stay with soft earth tone colour as they are very colour compatible with any colour of eyes, hair and clothing.
Also there should be coordination between the eye makeup and lip lips, once the colours on the eyes are bold and making a statement, the lips should be calm and vice versa.
I believe we understand makeup colour theory in line with colours and their combinations now.

Strive to get better!