Image pages must be given a unique page title. The title must end with the same extension with which your uploaded image ends (e.g. .jpg or .gif). Unique page titles are needed, so that someone else doesn't inadvertently over-write your image by saving another image with the same title.
You can create unique page titles by including the names of the individuals referenced in the image along with relevant dates, places, and/or document type in the title. For example, if your filename is grandpa.jpg, then your image page title could be something like "Image:Hathaway, Elmer - 1851 05 18 birth certificate.jpg". Since page titles are sorted alphabetically in wiki lists, titling this way will ensure that all of your images will be sorted by name first and date second.
Another possibility is to include the full title of the person or family page including the index number in the image title. For example, "Elmer Hathaway (1) birth certificate.jpg" which would appear in a wiki list of image pages grouped together with other image titles beginning with the letter "E". It's up to you.
Note: Just like any other piece of information about a person, Images should be sourced. When creating an Image page, please remember to include the source of the Image and how it was identified in the Description Box.