The other day, I was watching a video critique by Craig Tanner from The Mindful Eye. In this video among other things he was looking at the combination of colours and noted that while the image had the potential for a variety of colour pairs and triads, there was an overriding colour of green to the image. I had to agree. I didn't really like the colours in the image at all, too much green. However after he removed the colour cast, green was much less dominant, allowing all the colours to separate and greatly boost colour contrast. It was a subtle change but had a big impact on the final image.
A few days later and I find myself looking at this image below. I liked the pose from this praying mantis as he goes about cleaning his raptorial legs, but it didn't really separate well from the background. While I was staring at the image, I started to realise that there was an overriding sense of orange. Remembering Craig's video, I wondered if I removed this orange cast, would it allow my subject to separate from the background.
Praying Mantis – with orange colour cast

Canon EOS 7D with a Canon EF 100mm f/2.8 USM Macro lens at 160mm EFL hand held with twin off camera flashes remotely triggered. Exposure Trio: 1/250s, f/8 and ISO 100.
I use Lightroom to develop all my images. If you look closely at the top right corner, you'll notice that this area is almost neutral grey but there is a little orange in there. Using lightroom's white balance selector tool, I clicked on an area that was almost neutral grey in there, but still had a little orange cast to it.
Here is the result. The change is subtle but I think the orange is no longer so dominant, allowing the colours to separate and show the subject more clearly. In this case, Lightroom decreased the Colour Temperature from 5750k to 4950k and changed the Tint from +23 to +19.
Praying Mantis – without colour cast

This image was originally taken indoors with off camera flash and since my walls aren't pure white, the camera's auto white balance feature probably struggled to find a good value. When shooting macro with flash, I use Manual Exposure mode. I set my shutter speed to the fastest flash sync speed (1/250 for a 7D) and ISO at 100. Then I vary my aperture depending on how much depth of field I would like. The flashes combined with ETTL will fire just enough light to expose the image correctly. Ambient light will expose the background and if it's relatively dark, then it will underexpose or just stay black. Some people don't like this but I don't mind the effect.