Pictures of people

Better than landscapes pictures are people pictures, mostly of people doing their job, if they work in a colourful fruit shop, or are the host of our train wagon, or just if they are on the street with a nice or different style. While I usually try to make pictures of these people ‘en cachette’, it would be much better just to announce myself and ask if I could do a picture of them. Couple times I’ve tried but people are ashamed and say ‘no’.

Have you ideas, experience how can I make pictures of people with their agreement or should I just stand as a journalist and picture them?