I had an idea that we could share parenting tips. Maybe every sunday somebody posts a new one.
Here is mine.
Draw the problem
When a baby or child in inconsolably angry about something, anything, go and draw it. Draw it together, take a long time talking about every detail and drawing it. Use different colours and patterns. Normally the child with get very interested in this and calm down. He'll still be annoyed about the thing, but calm now.
It works for a surprisingly wide age range.
Obviously the first thing when a child is upset is to check if there's a medical problem. Is he hungry, thirsty, feverish, anything like that.
Distraction (the textbook answer) can work too, but in my experience only works for very young babies, and not often.