Here I've used a teaspoon of phthalo blue with a pea or half a pea of white and a similar amount of any reddish colour you have leftover. (arttutor.com)
I used a solution of 1 pea of magenta, 1/2 a pea of phthalo blue, and about 2 egg cups of turpentine. (arttutor.com)
I use lamp black as a dramatic accent as well, placing the pure black in a part of the painting that is already devoted to very dark mixed blacks (alizarin crimson and phthalo green or ultramarine blue and burnt umber for example). (artistsnetwork.com)