You'll eventually find, after a little practice, that many, many colours can easily be mixed from just a few basic colours. For example 'Brick Red' and 'Flesh'.
You would normally already have a stock of basic colours such as black, white, red, yellow, and probably the most frequently used camouflage colours, such as Dark Green and Dark Earth. So, using these, 'Brick Red' can be mixed as required, using red, a touch of black, and Dark Earth, adjusting as needed to obtain the desired shade.
Same for 'Flesh', using white, yellow, Dark Earth and red, again adjusting the proportions to obtain the tone required for the 'Flesh' - pale skin, dark skin, sun-tanned skin, 'I've drank too much and going to puke' skin - whatever!!
Such rarely used colours as 'Chocolate' again can easily be mixed, using a brown, dark earth again being a 'standard' starting point, mixed with black and red, again adjusting proportions as required.
It really is very simple, and always puzzles me why some modellers have stock of rarely used, 'exotic' colours which can be easily mixed, as needed, from existing 'basic' colours.
Of course, this is for colours only used in relatively small quantities - specific camouflage colour requirements may be different, although again, some can easily be mixed.