The biggest change and by far the #1 take-away from my attending the SOMA course is that you should if bleeding is massive, can not be stopped with pressure, or if proper medical aid can not be reached in minutes.
The most critical medical skills to learn: controlling bleeding, CPR, applying a chest seal and how to use an AED (Automatic External Defibrillators).
Increasingly more individuals are carrying lifesaving equipment with them, you should too.
The following is a recommended, minimalist list of items (and approximate cost) you can easily carry on your person:
Nitrile gloves ($1)
SWAT-T tourniquet ($10) (Any proper tourniquet, this one is most compact and inexpensive)
4" Israeli bandage ($5)
Calf sleeve/holster for kit ($10), to carry these emergency supplies is discreet and easy to carry around ankle or in pocket
Instruction cards ($1)
Curad Bloodstop Hemostatic Gauze ($1)
Compact chest wound seal ($10)
How to use a chest seal:
How to perform (the new CPR) in 1 minute: