Well, you asked where we found our training and I never paid a penny for any of it...
For starters, what region are you in, or do you want to travel nationwide? What levels and what skillsets are you looking for? What's your budget?
If you want medical, start off with your local Red Cross for basic first aid, then your local community/tech college for an EMT-B course, then try a wilderness medical course that's available from a few different resources. There's some tactical medical courses out there, but I would recommend starting with basics of ABC if you don't have a background in first aid before stepping into that (and the wilderness medicine will still teach you more).
Firearms? Holy shit are there a ton of options out there, the devil's in the details for what you want and need. There's big names and locations and then the small LGS type training that may be a retired 18B or pure FUDD, odds of what you get are like shooting craps. Or you can just go to Gunsite, they do pretty much all of it and have a professional staff to teach to any skill level.