Identifying your old family photographs is a lot easier if you know the era in which they were taken. Knowing the era gives you a better clue as to who the people in it might be. If you can narrow down the photo’s era and the location where it was taken (even if it’s just a general location), you can usually ID the people in the photos with a high degree of certainty, depending on how familiar you are with the people on your family tree.
Here is a basic tutorial of the early photograph types, when they were used, and how to identify them.