Here is a freebie image you can download as a simple color along to understand the concept. The bugs are nice but really appear to get lost in the mass of surrounding flowers.
Right away, I know that I want the bugs and a couple of the biggest flowers to stand out. So, I start by coloring the dark background and building out from there. (for simplicity, the tutorial will show flowers that are all the same color, but the same theory applies for multicolored flowers)
First, I isolate the focal points by coloring everything else in dull, grayish purple tones. One of the great qualities of Copic markers is that any lighter color can push a darker color out of the way. This means that even if I do tone my whole image grayish, when the time comes to add colors back into it, they won't be totally obscured.
Instantly it becomes easier to focus on the parts of the image that I want important. This trick works on just about any kind of image. (If you aren't confident enough to go as dark as I have gone here, then try the same thing with a very light gray instead.)
If you want the flower centers to stand out more on the flowers in the distance, simply go over them a few times and it will push the darker colors out of the way. This is a matter of personal preference.
You can leave the image like this, but I like to add even more depth. Right now I have basically two layers, the bright top layer, and the grayed out under layer.
For my final you can see I have 4 layers:
1. Bright Top layer (RV02)
2. Grayed under layer (V93)
3. Slightly darker grayed under layer (V04)
4. Darkest background layer (V17)
This was much easier to visualize than if I had tried to simply start on one flower and color each flower individually to start. The finished picture looks more complicated than it really is, and it is much easier now to identify the bugs as being the most important. A word of caution: Don't color the final bugs in dull, grayed colors or else they will get lost. Choose vibrant colors that stand out so they remain your focal points.
As I mentioned above, this can also be done with flowers of different colors. Here is the same illustration, this time with pale yellow and pink flowers.
Same as before, I colored the flowers in the background entirely with the grayish purple, then I went back in and colored over some of the flowers with a pale yellow. I left the other flowers alone. Then, I colored the hints of the farthest background with my darker purple to make it look even more dimensional.
I hope this helps you speed up your coloring and simplify the layering process. Enjoy the free image download!