Start with only a few pigments and master those first. You can paint an entire portrait with just: 1)titanium white 2)ivory black 3)cadmium red and 4)yellow ochre. But, I also like to add 5) burnt umber 6)burnt sienna and 7)blush, made by Gamblin. Most of my paintings only use these 7 tubes. The trick is to paint in layers. Let one layer dry and then paint another glaze.

By learning and painting alot, any chance you get

You have to use the thinner