One way to improve your macro shot portfolio is photographing subjects that are not immediately recognizable by the viewer.
First things first, you need the right lens. You're gonna need a macro lens that is wider than 40mm, an aperture higher than f/3, and most importantly, it needs to a true macro lens; it needs to have a reproductive ratio of 1:1. A reproductive ratio of 1:1 means that the subject's size will be the same as the subject's size in the frame (if the hyperfocal distance is close to the camera).
Now that's out of the way, let's talk about your composition. What's great about macro lenses, is that they create a huge amount of bokeh, so if you want the background's color to be in the shot, it can give you an interesting look.
For the most part, I wouldn't recommend adding the background to a macro shot. If you're looking for ambiguity, it helps to make the subject fill the ENTIRE frame. Take a look:
With the first shot, the subject can be easily identified, it's a dead cactus. But at the second shot, it's a bit more difficult. Why does this happen? It's because the background normally gives relativity of space. With the background in the frame, we compare it with the texture and our mind begins to assume the real size of the subject, eliminating that ambiguity. But when we close in on the subject, we are left with nothing to compare. We can't determine the subject's size. The viewer will look into the texture to try and decipher what the subject is, but the texture can be deceiving. That's the sort where the ambiguity comes from. People have told me that the shot above looks like a peanut, a sun-dried, a reptilian, even old hummus. No one has ever guessed it was a dead plant.
That's how you make the macro shot ambiguous. Remember to use an interesting, bumpy, subject. Look around, sometimes the subject for your shot is found where you would least expect it. Happy Shooting!