You spot a good background - a colourful wall, strong light, an interesting doorway, a gap in a crowd. Stop. Wait. Let people walk into it.

Give it five minutes minimum. Most photographers walk past a good scene because nothing's happening yet. The ones who wait get the picture.

Watch for: the peak of the action - someone mid-stride, mid-laugh, mid-argument. One person in a good background is fine. Two people interacting in a good background is a picture.

The point: street photography is 30% finding the scene, 70% waiting for something to walk into it.