The best way to explain a polarizer is that it’s sunglasses for your camera. I always forget to use it, even after reading articles like ‘Why You MUST Have a Polarizer‘. This time I didn’t forget, and the results were quite noticeable. Here are a couple of photos to demonstrate what a polarizer can do.
As you can see, the reflections were significantly reduced on the trunk. I used a Rokinon circular polarizer and found it to be quite good for the price ($10-15 depending on size).