Scorpions are characterized by their tail and pinchers. Typically scorpions with large, heavy pinchers and a skinny tail kill their prey by crushing. Scorpions with a fat tail and stinger and small pinchers kill with venom–typically a neurotoxin.
All scorpions are nocturnal and just want to be left alone. It is when we mess with them in their habitat that we get stung.
The most dangerous species (Centruroides) is found in the Sonoran Desert on the Southern border, and that species is really only dangerous to the very young, very old, and patients with a lot of co-morbidities.
You can generally prevent scorpion stings the same way as avoiding spider bites–by not blindly reaching into dark spaces (under rocks, into tree stumps or woodpiles, etc.). If you must do those things, wear gloves. You should also check out your sleeping bag before getting in, and shake out your boots before putting them on–scorpions like to find a dark tight space to sleep in and boots make a great place.
In North America, scorpions are not typically lethal–the stings are mainly just painful. There may be local redness and swelling at the site of the sting.
The only thing you can really do is manage the pain. While there are antivenins, they are arguably worse and more dangerous than just waiting out the reaction. If the patient develops an allergic reaction to the sting or exhibits critical system problems, they should be evacuated.