There are a lot of advantages to using a limited palette. The restrictions that it provides really makes you think about your choices. It encourages you to look and make interesting artistic choices.
The palette that I am currently using for my portrait painting is:
Titanium white (Windsor and Newton professional acrylic)
Mars black (Windsor and Newton professional acrylic)
Ultramarine blue (Windsor and Newton professional acrylic)
Raw umber (Windsor and Newton professional acrylic - I find that this colour has a multitude of uses. I love using it to dull down my whites. I also love using it to create subtle areas of tonal shift)
Venetian red (Cryla acrylic - this is my go to red at the moment and i really love using it when creating flesh tones )
Another advantage of using a limited palette is that it really does create a harmonious feel within the picture. The reduced palette creates a strong chromatic relationship with all the colours relating well with each other when mixed.
There are so many benefits to creating paintings using a limited palette, for me I just love the challenge. By finding the tones from a reduced palette I feel I am improving my artistic practice. It isn’t at all easy but we wouldn’t be painters if we were drawn to easy pursuits would we? By using a small pool of colours you really must analyse the colour that you intend to mix. Through trial and error you really start to develop a sense of how to create the correct colour.
A quick word about titanium white and raw umber. When you mix these together you get a wonderful grey colour that is great for highlights.