There is no shortage of tacticool schools out there, which is really unfortunate for those who didn't get the opportunity to experience ten years in the Army and two years in combat. The problem I see most often with these schools is that they're all focused on the wrong thing: combat.
You could kill hours and hours on YouTube or Everydaynodaysoff watching herpy derps "train" people to do ridiculous things like bump-fire at an area target or charge in, guns blazing. In real life, these things will only ensure that you will be criminally charged.
What you should definitely know how to do is hit one to three targets very solidly in as little time as possible, drawing from concealment at three to seven yards. But that doesn't sell people on a $500-$700 class. Gimmicks like no-light shoot houses and cameramen downrange seem to do that.
The biggest thing you should probably know though, is combat medicine. First aid is acceptable, but falls short of real immediate trauma care. Also, you'll find that most off-the-shelf medical kits are really just expensive boxes with band-aids and Neosporin. In real life, medical knowledge will go a lot further than knowing how to clear your house by yourself (which will result in you needing Quick Clot and a tourniquet. Or a bodybag.).
Just the other day at work, one of our HVAC techs fell off some scaffolding and hit his posterior on a steel door frame on the way down. This caused a 5" laceration on his ass, which bled enough to alarm the poor fellow, but was all capillary bleeding from his skin. It was deep enough that I could see quite a lot of ass fat. Using my Army CLS skills, I went to the heavy-duty kit in the job trailer and got shitloads of gauze and an ACE wrap to serve as a protective cover for the gauze packing and wrap. My wrap did well enough that by the time he got to the hospital, his ass had stayed intact enough that they could stitch the wound without any extra cutting to facilitate a clean stitching.
Learn combat medicine (classes do exist--seek Navy corpsmen if at all possible). You may save a friend's ass, or even your own.