One thing I'm quickly realizing is that my "ultralight" FAK is too small. I'm thinking of replacing it with one like the one I have in my room (the Johnson & Johnson "All-Purpose First Aid Kit" with 170 items in it), adding even more to it after some research, and packing it in a Pelican case.
Either that or start with an AMK
Comprehensive kit.
It is a tad costly, but an outstanding place to start.