Apparently I'm on a photograph Jimmy streak. Not that Colton's having less images taken of himself, but Jimmy, at 4 years old, has been a real challenge to get nice pictures of because he always insists I may not take another picture of him ever again as soon as he sees my camera. And those rare times he's not being grumpy about photography, he is sticking out his tongue or looking the other way.
Bottom line, most children between the ages of 3-5 (give or take) refuse to cooperate for pictures.
But here's the trick: Give them something to do that they love. Whether it be painting, swinging, climbing trees, reading books, putting puzzles together, coloring, playing with their favorite toys.... Properly posing energetic children bent on exploring the world is a relatively futile endeavor unless it's your lucky day. But let them be who they are and don't ask for "cheese". Just show them you're there to have fun with them and snap a picture as opportunity allows. If they get insulted by your photographing appendage, exclaim what a cool picture that was and show it to them. They're likely to repeat that antic and not even care what you're doing.
Jimmy here had been playing in water and then swinging from the maple tree. He was happy, in his element and not at all bothered that he was being so photogenic for me. It wasn't a planned photoshoot, but these are my favorite pictures of him.