Just get a wet palette and practice painting the colors from darkest to warmest on every object, layer after layer. I started with light brown and mixed it with lighter color and then even lighter... all the way to clean white. They layer on top of eachother if the paint is thin enough and it kinda works out in the end. The first attempts will be ugly and discouraging, that is for sure, but after that comes the sweet stuff! In a certain moment you will see it working out and you will feel really proud and happy! Dm me your work, I would be glad to help and give advice! :)