Stock Radio/Casssette Replacement Instructions

I need to replace the stock radio/cassette in my 96 and I would love to know the proper way to remove the unit from the dash. I have seen many cars where the cover door no longer closes right due to someone screwing with the radio and the way it's mounted. If anyone can tell me the steps involved in accessing and removing the radio/cassette unit I would be most appreciative. I have a uesd replacement on hand but I want to do it right.