After 15 months I've started to upload pictures, in the last days I have reached the 300$ of gain with 150 images sold.
So I started to look at the pictures I've sold in the past two months to try to understand what are the preferences of the buyers. I quote here some photos sold classifing by different themes:
Pictures of details taken in specific places:
Images including specific concepts:
Images including starry sky:
Tombs and memorials:
I conclude with the following consideration.
My portfolio contains only few most typical stock-photo images. I have no models and only a few images of isolated objects.
However, analyzing the sold pictures, I seem to notice a strong diversity in the themes, and in general there are no pictures of the same subject. I have the impression that this "diversity" helped me to increase sales in recent months.