1. Don't be stupid.
The federal Consumer Products Safety Commission advises that fireworks should be lit one at a time and then backed away from. That alone should be enough to prevent most dumb, avoidable injuries. The second way to not be stupid: Leave any firework alone if it fails to ignite completely. It's a loss, so don't try to relight it or pick it up.
Kids shouldn't light fireworks without adult supervision and young kids shouldn't light them at all. You definitely shouldn't shoot Roman candles at your buddies — not that that's something we've had experience with — or light fireworks inside of glass or metal containers. When it comes time to throw everything away, douse your spent fireworks with water from a bucket or with a hose.
2. OK you just did something stupid. Evaluate just how badly you've burned yourself.
If somebody does get burned, it's important to evaluate how bad the burn is. If it's merely a red discoloration with a small blister or blisters, you've got a minor burn and maybe a good story. Minor burns should have cool water run over them for at least 10 minutes. Afterwards, the burn can be wrapped in cling wrap or a similar product. This protects the wound. After this initial treatment, try applying aloe vera to the burn.
But this is the Fourth of July. You can do better. If the burn covers a large area, and if you see significant skin damage, start with washing it with cool water. If it covers a large enough area of the body, you should use the bucket or hose that you were going to use to put out the fireworks to make sure the burn is covered with water. The wound should be covered with something sterile, like cling wrap, and the victim should be transported, ideally by ambulance, to a local hospital.
3. What do you mean burn? I just blew off an entire appendage.
Firework accidents can cause amputations, just ask Giants defensive end Jason Pierre-Paul.
Assuming you have enough fingers to do so, call 911. Clean out any foreign matter from the amputation site. The errant finger, toe or limb should be wrapped in a towel and sent with the victim to the hospital.
Here's a crucial tip: Don't put that severed piece of meat on ice. That will kill the blood vessels and make reattachment a lot harder.
4. Watch out for your eyes.
Fireworks are often associated with losing fingers, but they are a danger to eyes as well. Flying debris can puncture an eyeball and pop an eye from its socket. Obviously, head to the emergency room. But lesser injuries can be treated at home. The eye should be immediately flushed out with saline solution. If possible, any foreign objects should also be removed. If vision doesn't improve within a few hours, it's off to the ER with the rest of the casualties.