In a subtractive color system, Red, Yellow, & Blue are the primary colors. Conventional wisdom teaches that you can create all of the other colors from these three. That isn’t exactly true. Color mixes in a straight line.
In college I always bought the list of colors that the teacher put on the supply list but I had no idea why the specific colors were picked.
One day in my watercolor class we were on location and I was running out of yellow paint. I rummaged through my paint box looking for yellow and found 2 yellows. I didn’t know which one to choose and so I chose both of them and mixed them together in my palette so that I wouldn’t need to decide again. It was years later until I understood why I needed 2 yellows, 2 blues, and 2 reds.
To get an intense green choose primaries that don’t contain red. Red is the complement to green and it will lower the intensity when mixed together.