Orange & blue is one of my favorite color combos to use in my abstract work. Color theory tells us that complementary colors mix to make neutrals, and I've had the best results with blue and orange. Red and green (or more accurately, in my experiments, viridian and a cool red) often work as well, but I've had zero luck finding a pleasing combination of purple and yellow. And I've tried! A LOT. Instead, purple and yellow just make mud, almost without fail, and the worst part is it's not even interesting mud. It's just ugly brown. Give me a lovely granulating ultramarine blue + quinacridone rust any day.
And so I go back to the old reliables, blue and orange, time and again.