Hi Graham,
I am not a specialist in this matter, and like you I don't have a good head for colour mixing and am experimenting. I heartily agree with clsgt's suggestion of
Blue and Yellow Don't Make Green by Michael Wilcox -
https://www.amazon.co.uk/Blue-Yellow-Dont-Make-Green/dp/0967962870/ref=sr_1_1?s=books&ie=UTF8&qid=1521242943&sr=1-1&keywords=Blue and Yellow Don't Make Green It is great on understanding colour theory and the rationale behind it.
I also use Ian Sideway's
Colour Mixing Bible as a reference -
https://www.amazon.co.uk/Colour-Mixing-Bible-Ian-Sidaway/dp/0715318233/ref=sr_1_1?ie=UTF8&qid=1521242818&sr=8-1&keywords=Color Mixing Bible.
I haven't got Powell's book, which has good reviews,
https://www.amazon.co.uk/Color-Mixing-Recipes-Acrylic-Watercolor/dp/1600582834/ref=sr_1_sc_1?s=books&ie=UTF8&qid=1521242889&sr=1-1-spell&keywords=1500 Color Mixing Recipes for Oil, Acyrlic and Watercolor
I also like W&N Artisan Water Soluble Colour, although I am a novice with not a lot of painting time under my belt. More experienced members will have better advice, but other colours I also use include:
Prussian Blue for dark blue colours. A couple of washes of Cerulean Blue (not the hue) over it gives a nice highlight without making it too bright;
Raw Sienna provides a lighter brown;
Rather than Cadmium Red Hue I use Cadmium Red Dark, Cadmium Red Medium, Cadmium Red Light and Magenta;
My greens also include Viridian and Phthalo Green (Yellow Shade), although I don't think it matters if you have Phthalo Green (Blue Shade)
I also find Cadmium Yellow Deep Hue useful when working with Yellows.
I find the Naples Yellow Hue OK.
Those with a much better grasp of colour mixing would probably use fewer colours, but for a novice like me I find a more extensive palette easier at the moment.
As well as water, I also use Zest it with the Water Soluble Colours, which hasn't the strong odour of White Spirits or Mineral Turpentine, and it gives a very flat finish for clothing, etc.
http://www.zest-it.com