The decisive moment
You can catch “the decisive moment” by the position of a person in the frame, in their facial expression, in their hand gesture, or their action or movement. It is a moment that happens in the fraction of a second and disappears.
“The decisive moment” was a phrase coined by Henri Cartier-Bresson"
Play with silhouettes and shadows
Shadows and silhouettes are classic elements in street photography. They’re mysterious and interesting, yet familiar and commonplace. You can find good silhouettes and shadows everywhere in a city.
As a bonus, they help disguise the identities of the people you’re photographing, so they can remain anonymous
Use your eyes
To find a great moment, you actually have to see it with your eyes before you go to take a shot, so embrace this. Focus your energy on looking around and try to be as aware of your surroundings as possible.
Use this simple tip when camera isn't there but moment is
A street portrait requires you to interact with your subject. Interacting with a stranger may strike fear into those just starting. However, it's a great way to meet interesting people and make new friends.
Its a great way to start Street Photography and practice it with people in your hometown.