Their is no way for them criteria. It's depend upon us what is the best and want gave a name for that. But if we will take a related name with their content it will more beneficial for their promotion.
There is no such as best way. The only thing you can do is put some relevant keywords in the alt tags of every image. This is the only thing you can optimize your images with.
You can use related targeted keywords in the tag so that while searching for this keywords you can get search your photos...