Be very careful with Phthalo blue and Phthalo green (also known as Winsor Blue/Green and Thalo Blue/Green) as they have extremely strong pigmentation and you only need a tiny amount. They are to be used judiciously and sparingly and only when absolutely necessary to obtain a particular color. I have had the same tubes of both of these colors for decades and doubt I will ever need to buy another tube, that is how little you need to use! Having said that, sometimes a tiny touch of either color can really enliven your work.
Stick to Ultramarine Blue as a basic for most of your color mixing.