In which field should I do my Masters?

[Efiyoyo]

Hello Friends! I have a BA in Economics and BSc in Information Systems.
I have two doubts whenever I think of joining a graduate school in USA, say in Marketing, Information Systems,Economics or other Social Science fields which one to select. Please tell me your idea in pointing the top field that one can easily get a job with good income after graduation in USA? In addition to this I want to know what kinds of tests should I take and what are the prerequisites to join these collages.
Thanks.

[BME_Fanatic]

corporate economists/economist cosultants make a lot of $ in the US