The number 1 emergency piece of kit for those of us (probably most of us) who work alone in our shops is a
cell phone. If something catastrophic happens you are not going to be handling it by yourself. Call 911, grab something to soak up blood and apply pressure to the wound until help arrives. Sit down on the floor because if its bad enough to call 911, there is a good chance you're going into shock soon.
The best "kits" I've seen come from these guys:
https://mymedic.us/collections/first-aid-kits. Lots of kits available. I suggest you choose based on your level of competence; it does no good if you don't know how to use something, even if it is there. This especially applies to a tourniquet. If you ever use a first aid kit, replace any item you used as soon as possible.
The vast majority of injuries in the shop are minor ones - cut, scratch, small burn, splinter, etc. These are injuries that can be treated by you, with one hand.
- Time: as soon as an injury occurs you need to stop what you're doing and treat it, now. Don't slap a band aid on it and get to it later; that invites infection. If you treat a wound effectively within the first few minutes the risk of infection is greatly reduced.
- Help: if it is anything more than a truly minor injury, get someone to help you. At this level of injury you are not going to be thinking clearly - get help. If no help is available and its something you aren't absolutely sure you can manage, call 911.
- Soap and water: this is the best way to clean and flush a wound, and it is better than alcohol or Betadine when it comes to wound healing.
- Alcohol and Betadine swabs are good to have. They disinfect and sterilize a wound and the area around it when you cannot get to soap and water. You cannot effectively flush a wound with these but for minor cuts or scratches, they work. Clean the wound and at least several inches around the wound.
- Triple Antibiotic Ointment: get it at the drug store and replace annually. Apply with a Q-tip, not your grubby fingers that are full of bacteria.
- Band Aids: get the waterproof, fabric type. The others are a waste of money for a shop guy.
- Paper Tape: 3M Micropore tape is one of the best tapes to have. It will hold on a dressing and can be used in place of a band aid. It passes air and water but will not allow bacteria to pass. You have to clean the wound, stop the bleeding, clean again and then apply the tape and allow it to heal under the tape. Works good, especially for skin avulsions where you scrape off some skin but its still hanging on. Clean gently, push the flap of skin back into place, apply some antibiotic ointment and put a piece of paper tape over it. If you leave the tape in place until it heals, you may not be able to see where the wound was unless you really look for it.
- 4X4, 2X2 gauze pads: good for cleaning up blood, for applying pressure to a wound and for dressing a wound.
- Stretchy self-adhering tape: better than regular tape to hold a dressing in place.
- Splinter removal kit, Optivisor so you can see that damned thing.
One of the best first aid items is a good book on first aid, preferably read before you need it. Watch for any signs of infection - redness, heat, pus - you're a guy, you know what an infection looks like. If you see it, go to the doctor.