Any parent could really tell you most of this. Toddlers are pretty simple really. They are free willed individuals who are all about testing their limits and generally doing whatever it is you don’t want them to do. That is why they can make some of the most difficult subjects to photograph. The reason they are so difficult though, is really because we, as photographers, are usually unable to adapt to THEM. We want things set up a particular way, more specifically our way. Well, toddlers seldom want to go our way.
Toddlers, from around 9 months of age all the way to four years old are a challenge to photograph. Sometimes they can seem downright frustrating. Around the ages of 9 to 12 months, children learn to walk. At this point, they are constantly exploring their surroundings, and they move around, a LOT. You, as the photographer, need to be able to work very quickly, an very confidently.
You cannot force anyone, especially a child, to smile naturally. To coax a smile, you can make a joke, or catch your subject off guard. Make a silly unexpected fact. Make a sudden, silly noise (not a loud noise that will scare them though). Candid shots are often the best shots you get! If you’re in a situation where a child simply does not WANT to smile, like a studio setting, then try having them say a word like happy, turkey, or even “cheesy” (it’s better than the old standby, “cheese” because you get TWO opportunities for that smile rather than just one! Any word with double “ee” in the middle, or ending in an “EE” sound will work! The word “chicken” will even work, but you need to act quickly in order to catch the expression!
Really, the best thing you can do is NOT to rush, and jump right in! Take just a few minutes to get to KNOW the child. Try and get a feel for their personality. Toddlers can pick up on stress, and the more stressed you are, the worse they get. Stay calm, go with THEIR flow. I am speaking this not only as a photographer, but as a mother.