[AaronI]

A good place to start is http://www.foia.gov/

The specific information required for a request varies by agency, as do any fees. Most of them now provide online forms on their sites.

While I was the FOIA/Privacy Act coordinator/liaison for one of the commands I was attached to while in the Navy, we generally accepted any form of written request, provided the person included their full name, postal address, phone number and a detailed enough description of the information they were requesting.