Kids portrait is always fun,why? Because there is always different emotional expression that is pretty natural that can hardly be seen in adult.
Photoshoot with kids is like having a game with them, you don’t need to give them any special instruction, just like how you use to play with your kids, make them laugh, talk to them, listen to their stories, let them treat you as their friend and not a stranger that just come to take their photo to show to others.
In my opinion, the main key to a good kids portrait is communication. I can say u did a great job if the kids come to you and ask you to take their picture instead of yourself chasing them around and complaining that kids are troublesome.
Suggestion : How to take a funny expression of kids?
Hide-&-seek is a good game to make them come to you with a happy and exciting expression.
Shoot in burst mode so that you will not miss out the 1 second only moment =)
Have fun shooting with kids ya!