Training standards; common sense...
There are no real mandates or training standards to own or use a loaded firearm but common sense & good judgement go a long, long way.
Outside of a police/LE training class, a enlistment in the US armed forces or a hunter safety/new gun owner program, I'd suggest reading top firearm guides, watching DVDs/class videos from respected programs(instructors) or going to a good friend/family member that knows a lot about guns.
Hollywood movies & "unscripted" TV shows like Sons of Guns, Die Hard, Miami Vice, Top Shot etc are NOT skill training.
Many times, $ or budgets may be a issue. It is for me. Learn who the "players" or operators are in the shooting sports industry. They offer practical advice not just weekend Rambo mumbo-jumbo.
Top instructors include; Clint Smith, Massad Ayoob, Leroy Thompson, Duane Dieter, John Shaw(Mid South), John Farnam, Jeff Gonzales, Larry Vickers.