You can divide it up by color, like do all the yellow first, then the red, etc. There are lots of ways to break it down so you can tackle it. I find it's fastest if you do the easiest areas first. In the case you describe, the floor is always the floor, and maybe there is a plant or two that are unmistakable, like a fern, or one that is more red or more yellow. Or if there is sky visible, or a roof, start there. Puzzles are easier if they have a lot of different colors in them. Keep your sense of humor.