Generally speaking, the places that prohibit photography will have a no photography sign.

I notice many stores do have no photography signs inside the stores, but it varies. In the public you shouldn't have any problems. Taking pictures of trains and transportation is no problem, almost encouraged sometimes. Very different when compared to the US, where taking a picture of a train might give you a tour of the local jail @_@.

Just keep an eye out for signs, and not getting in anyone's way or annoying anyone and generally things are ok.