I love painting with complementary colours. When two colors that are opposite on the colour wheel meet in a painting, the results are vibrant and vivid. They can actually be disorienting in large doses (think those black & white optical illusion pieces) but for an artist, they are a great tool.
My sunflowers here were just a result of playing with complementary colours, lots of water and letting things happen. And I love that little bee at the top!