You're going to mix a deeper orange. Now, you take some crimson and add it to the light orange that you mixed before. This is going to go in the foreground. Wipe your knife on your damp rag and dip it into the red orange mix, and then take it over and wipe it into the foreground area, take it up to the ridge line, and then bring it down into the foreground. You can actually add some more crimson to it to deepen the color, especially down in the foreground. If you look at a color wheel, you'll notice that red and green are opposites, which means they're complementary colors.

So allowing touches of the red to show through especially in this foreground area will add vibrancy to the overall color composition