I am not grasping mixing blacks with other colors but my mother snagged a walter foster book from a rummage sale about mixing colors, so I hope she sends it soon James
James, when I started with acrylics, I didn't even purchase black (from advice that I had read). I suggest you put your tube of black away and experiment with your other colours and see what you come up with. I'll show you an example of something I did with very little or no black.
This was my colour palette: Ultramarine blue, Burnt sienna, white, a bit of burnt umber and sometimes a teeny tiny bit of black for the really dark areas, but mostly mixed my darks with the colours I mentioned. The backround is sap green and crimson red, sometimes a bit of b. umber and/or white
My "blacks" were all mixed with ultramarine blue and burnt sienna (my favorite combo for darks), sometimes I went with the burnt umber. Then then highlights were made with this combo, just adding white to lighten as I went along, layer after layer.
Just get a scrap piece of canvas and mix some colours and see what you come up with.