How can I improve Bunny Wearing Jewelry?

It looks like you used a flash - so the shadow might be caused by the end of the lens. But independently from that, while the idea is good, I find that the background is distracting, the jewelry is not very visible and the head is cutoff.
This is just my opinion , of course.

That used to happen to me all the time - took me forever to foind out why!.
Good luck.