You make sure you have whatever toys and foods the children are used to having. You speak positively about the trip to them. You make them comfortable, forgetting your own comfort. And you try not to book them on a long flight. I have flown with dozens of parents with dozens of toddlers and have admired how well organized the parents have been. They seemed to know their children well, and the children were attentive listeners and were excited to play with their special games or books that the parents had packed. Some people will always complain, because they do not like children, but they are in the minority in my opinion.