Start with relatives, friends, and defense attorneys. Try to drop in on a facility's regularly scheduled visiting day. Keep the skepticism, but be willing to listen. Don't write parachute stories and expect access. If it takes an execution, fire or a riot to get you down to the prison, don't expect much cooperation from the authorities.
Prisons are full of stories, good and bad, and constitute huge chunks of a state's budget.
In most states, prisons trail only education as a percentage of the budget. Imagine covering prisons the same way as education. Be on the alert. Many restrictive prison access policies have caught reporters unaware. Changes are made often without the ability for press groups to comment.