A most common way to practice complementary colors is simple choose a pair and limited your palette to those two (plus tints, shades, mixtures maybe). Like this:

Whichever pair of colors we choose, it is most likely one warm and one cool. In a painting lesson I took years back, we used the complementaries a bit differently. We create a painting in cool colors, and paint the warm complementaries on top. Here’s the result:

Unfortunately I failed to take a picture of the cool painting underneath, though I did let the cool colors showed through here and there. The colors were not strictly restricted to one pair of complementary colors, but it is within certain range.

I’d say the result is quite different than if I started with these topical colors. There’s a solidity and unity unique to this method.