What do you guys think about this render, what can I improve?
Welcome to the community!
Overall, this is simple, but well done. I think you have picked colors, materials and shapes well. I also like the smooth gradients of the lighting and the reflections on the spring.
There is one thing I think could be improved. The reflective nature of the spring makes it take the color of the background near its sides. This makes the shape slightly harder to read. Maybe it would look better if there was a bit of rim lighting, or maybe a slight glowing rim in the shader? I am not sure if it will look better, but I would try it.