The Civil War changed fashion from extravagant to more conservative.
The Victorian era was the life span of Queen Victoria of England from 1837 to 1901, which influenced fashion and mourning customs after the death of Prince Albert in 1861.
Tintypes were produced in the USA from 1856 and became popular from the 1860s.
By the end of the decade they had become quite popular for the cheap end of the market and they were fitted into a card the same size as the ubiquitous Carte de Visite and therefore fitted nicely into family albums.
Larger tintypes in the UK were more likely to be produced by itinerant photographers (seaside etc.) because the tin was light and unbreakable and tintypes became more and more popular in the 1880s and 1890s and lasted until as late as the 1930s on some beaches.
Such as clothes worn, the background, objects in the background and the history of the photo (how did you acquire it).
The physical properties a photograph is made of, is another subject to learn.
Do not let this sound too intimidating, chances are most photographs have few clues to research .