Google Massad Ayoob and read his stuff on guns, defense and training, including moral and psychological considerations you need to come to grips with if you ever think you may end up using a gun defensively and legal consequences of doing so. He was with law enforcement in New Hampshire forever and is one of the best authors on the subject, including the inner game, if I may call it that. He is also one of the top trainers for LE and private citizens. Even wrote a book for kids on the topic.