First spots of color... Actually a very very thin layer of oil paint spread out as thinly as possible and even after that rubbed with a tissue to get most of it off. That's the idea of layering - several amazinly thin layers of color on top of each other, each showing the layers beneath.
This is about 70 cm x 70 cm, and if you look at all the yellowish (gold) color, I maybe used a paint daub the size of the end of a pin to create all of that (you know, those pins with a "ball" at the other end). I hope that gives you an idea how little paint was used.