The main ones are: as - at - for - with - in - on -under. The different meanings and uses are quite easy to understand. but it might take some practice to get them right. Here are some examples:
I work as a nurse, as an accountant.
I work at a hospital, I work at a department store.
I work at XYZ. (Name of the business or workplace)
I work for Macy's (name of store). Can use at or for here.
I work for a good boss, for Ms Smith. Cannot use at here.
I work in the city, in a high rise building.
I work in New York, in Moscow (name of place, country etc)
I'm working on an assignment for my university course, on a project in Europe.
I work under a very strict manager who gives me too much work.
I work with a nice group of people