What oil paint do you use?
I use Winsor and Newton Alkyd Fast Drying Oil Colours because they are very good quality and help my paint to dry faster. Any artist grade (not student grade) oil paint should be fine though. Student grade paint contains more filler so you will not get the same results as artist quality paint. I have tried water mixable oil paints but felt they did not mix well with water. Also, I do not use the colour black. The black often used in my glazes is mixed with other colours like Sap Green. When I use black in other mixes it is a very small amount and is used to bring down the saturation (purity) of the colour. Green can also be created by mixing black with yellow to create an olive type green which can be used successfully for landscapes. The colours I use for most of my paintings can be found here. I rarely ever use any other colour than the ones listed, no matter what the subject is that I am working on.