Opaque and transparent, but through the years it has been trial and error. Yes, sort of like my life.!!!.
That's what comes from being self taught. I've never liked tube greens and always mixed my own using various yellows and blues, mostly colors that I liked (still do ) New Gamboge, Ultra Blue being amongst them.
A few years back I read a book Making Color Sing by Jeanne Dobie, and at the time I was still mixing and mushing and making mud. MUD -- the favorite color of artists that don't know a whole lot about color mixing.
Now I've taken it more seriously and putting (trying) it into practice.
Out of these few transparent colors you can do a lot and you won't make mud. You pros already know all this.
I've taken a liking to cobalt blue, aureolin yellow, always did like rose madder genuine, viridian and the very staining transparents, Winsor blue and Winsor green, alizarin crimson. I've been on a sunflower rant the past few days. Sharing one with you.
Not one of the best, but hey Ma Look ! No mud! BJ