Most importantly, keep the first aid kit in an easily found spot. I once cut myself at a scenic pullover while washing a paring knife and could not stop the bleeding unless I held a clean cloth over it and pressed hard. Unfortunately, I had put my first-aid kit in a bottom drawer that I could not open with slides closed. I finally managed to stop the bleeding, and then I got out the kit and labeled it clearly and put it in an overhead cabinet in my living area.
I also recommend some Coban tape, wide ACE bandages, larger non-stick gauze pads, and a couple of ice and heat packs.
Also, I live and travel alone, so I also have a one-page document that lists all my medications, gives a quick health summary, lists medical plan and phone numbers, names of doctors and phone numbers, as well as family contacts. I carry copies in my purse, bike bag, and in my motorhome. I also keep several envelopes nearby that contain my most recent health checkup results, blood tests, etc. That will all give EMS personnel important information if I am found incapacitated. It also saves me time trying to remember things when I am in an urgent care facility or emergency room. If nothing else, it will mean medical personnel will better know how to treat me and they won't have to repeat things like cat scans and blood work that I recently had.