Colour theory, something Artist should know but most artist don't really care too much to know about it. But what is the purpose of colour theory? Basically to know what colours go well with each other, and how to use them to portray a mood you're setting. FIRST; The Basics
Primary Colours: Red, Yellow, Bluee Secondary Colours: Orange, Green, Violet Tertiary Colours: Orange-Yellow, Red-Orange, Violet-Red
Blue-Violet, Blue-Green, Green-Yellow
Hue Saturation -
This would be colour before adding any lights or dark. Most of the time you wouldn't use all of your colours in full saturation as it can sometimes be straining on the eyes, plus they don't always look well together.
If they're opposite from the from each other on the colour wheel, they'll probably go well with each other
Red - Green
Yellow - Purple
Orange - Blue
RGB - Red, Green, Blue
This is what the internet and computer normally uses CMYK - Cyan, Magenta, yellow, Black
This is what printers normally uses
SECOND; Picking the right colours
There's a few things to keep in mind what you're wanting the setting of your drawing/picture to be, is the setting cold are dark? Have more blues and/or purples. Is the setting more warm and bright? Have more yellows and oranges. Do you want colours to be more in harmony? Looking at the colour wheel, pick one colour and then the two beside it will still work with them. Example, picked green? You can use Yellows and Blues with it. If you're wanting something to pop from the picture, that's when you keep the complementary colours in mind. Example, if you have mostly blues and violets in your picture the object you'd like to pop would be orange or yellow.
Colours and Meanings
Colours can a many sorts of meanings, and can make people feel things.
So here's some examples that I took from my old book from college, "Color Workbook" by Becky Kornig
Red- Blood, Martyrdom, Sin, War, Anger, Fire, The Sun, Sexuality, Evil, Fertility, masculinity, Festivity Yellow- Treachery, Cowardice, Light, Truth, Warning, Cheerfulness, Spirituality, the Sun, Gold, Radiance, Earth Blue- Heaven, The celestial sphere, Water, Baptism, Space, Coolness, Eternity, Faith, Serenity, Wisdom, Feminine Green- Spring, Resurrection, Envy, Holiness, Charity, Regeneration Black- Death, Evil, Darkness, Void, Witchcraft, Sadness, Mourning, Time, Rebirth White- Light, Air, Purity, Marriage, Death, Redemption, innocence, Surrender
•Might add more to this when I think about it•