First... take a basic life saving class from a red cross certified instructor, including CPR and AED.
Now that you have some of the fundamentals..... the hard part is finding a class tailored to the shooting community that goes into detail about treating penetrating wounds, including hands-on time with tourniquets, seals, dressings, etc. And maybe one that covers a few things about mindset and tactics of dealing with such medical emergencies in an unsecure or even "hot" environment.
http://lonestarmedics.com/courses/
Specifically...
http://lonestarmedics.com/field-tactical-med-lab/
I took an abbreviated class with this guy a few weeks ago, excellent.
IFAKs and larger FAKs for the car, etc. depend on the types of problems you think you may encounter. I have a Boo-Boo kit in the car, next to a penetrating trauma kit for more serious injuries. There are also good belt pack and ankle holster kits available.... it really will depend on what you feel the need to plan for. A basic penetrating trauma kit should include gloves and scissors (or Benchmade 7 knife), a tourniquet (IMO the best choice is a
SOFTT-W, but I'm not a medical professional so, feel free to disagree) and a battle dressing (Israeli or other). If you have the space, add Hemostatic powder and/or z-fold gauze with hemostatic agent, a pair of chest seals (suggest HALO) and some extra gauze. If you don't have the training to use this stuff, get trained. It's still good to have it on hand, to give over to someone who does have the training but not the gear.