In many tourist destinations, people may ask for money if you want to photograph them. Many of these places are desperately poor, and people have few ways of getting hold of cash. The money they ask for is usually not very much to us, but may represent quite a lot to them. How you deal with these situations is up to you, but remember that every time you buy a postcard, you are happy to spend the money for a picture somebody else took. Why not spend a little on your own?
Make use of people to give your images life and scale. If the facade of a particular building appeals to you, the picture may be that much better if you show people walking in front of it. They will give it scale and also let viewers know what sorts of people live there, how they dress, and the like. An outdoor café may be more interesting crowded with people than empty.