There is no larger employer in the world than the United States Government. Positions are available on a near regular basis, despite recent cutbacks.
Not only are there opportunities domestically, but employment outside the United States is a possibility on military bases, overseas embassies and various departments of defense and state agencies.
The Federal Personnel Manual covers all aspects of personnel management within
the federal government structure and is available on a subscription basis.
You will have to become familiar with a whole new employment language. This is the federal government, after all. A special occupational classification system exists which determines pay and job grades.