My default FAK platform is an AMK - either one of their old ultralight kits or the new International Field Trauma kit. I always have one close by.
For those rare times when I don't carry a full kit with me, my personal minimum, and what I supplement each kit with, is: water, a bandana and/or a triangular bandage, a couple of thick maxi pads, a small pen or squeeze light, and some OTC meds (Asprin, Tylenol, Gravol, Benedryl - as well as kids versions for our son - and hand sanitizer. Bug spray, sun screen and cooling gel for burns.) I also have a pill fob with prescription meds and aspirin on my edc key chain.
Besides water and meds, my main four are:
Maxi Pads => pressure bandage, splint, their intended purpose...
Bandana/triangular => broad/narrow bandage, pressure bandage, sling, face mask, hankie, hat...
Light => FA in the dark, pupil check...
Bandaids=> I'm a mom. "They" include them when they hand out our parent cards.