Many investigative reporters got where they are by starting as beat reporters. This is a good way to get story ideas and familiarity with an area.
On "day one," you have an assigned "beat" -- an area of coverage. Maybe it's city government, or the courthouse, or local business. At the WSJ we had reporters covering finance, medicine and healthcare, technology, education, mergers and acquisitions, automobiles, energy, etc. We had a database where most Fortune 500 companies were assigned to exactly one reporter as the responsible person for any news involving that company.
We subscribed to the newswires (AP, Reuters, Dow Jones) and filtered for any news involving our companies and beats. We read the SEC filings.
On "day one," I called my companies and introduced myself as the new WSJ reporter covering them. They would invite me to their HQ to meet the CEO, one or two other executives, and the PR apparatus. Sometimes they would complain in a friendly way about previous WSJ coverage or about too-favorable coverage of their competitor. Sometimes they invite you to visit their factory or meet their customers. They encourage you to attend their industry conference or trade shows.
Some companies will go all-out. When UPS gets a new WSJ reporter covering them, they order the person a brown uniform in their size and have them ride in a delivery truck for a day so the reporter gets a sense of how the company works.
