When I started taking pictures of strangers in the street, I did not feel comfortable doing it. That was the period when people approached me after I took their picture.
Most of them were not so nice. However, it is legal and I don't use the picutres to put strangers in a bad light. So I kept on doing it.
At some point I felt very comfortable doing it. When I was confident taking pictures from strangers in the street, no one said something!
Isn't that intersting?
That taught me something about confidence! You can read many books about how to be more confident. But that won't make you more confident. No way!
The only way to be more confident, is to do things which are not comfortable for you. That will make you more confident.
And the things which made you nervous in the past will bring you joy one day!
What are you afraid of? Public speaking? Whatever it is, do it. You will feel uncomfortable. But that feeling will stop and you will enjoy it one day!
For photographers: How do you deal with people who complain?
Be nice! Show them the picture you took and explain your project. If someone is angry: Just keep on walking and don't react. Or you can pretend like you took a picture of something behind of them.