1. Fireworks. Without them, it'd be a normal 3 day weekend, but this is a variable we aren't used to, so be prepared! Never dispose of 'duds' in the fire. Light fireworks a safe distance away from trees, houses, and people. Do not give fireworks to small children. And make sure you have a bucket of water/cooler, or portable extinguisher (that works) at the ready.
2. Alcohol. Alcohol and fireworks do not mix. There's no way the insurance company is going to buy that story about 'hail damage' when there's a 2 foot smoldering hole in your exterior. Have a designated lighter. And if you're going out of town, a designated driver!
3. Traveling. That firework show in Laurel is beautiful, and there's nothing like camping and spending the 4th under the stars... but the drive there and back can be infuriating. Don't let road rage get the best of you, and drive conservatively, to make up for those who might not be. Just know going in that the highways and back roads will be terrible. Accept it.
4. Weather. July in Montana is HOT. Heat stroke is always a big concern this time of year. So are sunburns, and overheated cars. Use your best judgement, put on sunscreen if you're going to be out in the fields, or try to stay in the shade if possible, drink lots of water, and keep an eye on hot cars. Fireworks will NOT go off in a hot car, their fuses are tested in ovens and should only ignite when in contact with direct flame, but you should still store them responsibly.
5. Grilling. Check your propane tanks, if applicable, for leaks, keep children, pets, and fireworks away from the grill. And please, don't use lighter fluid once the coals are lighted to try and heat things up. The fireworks show doesn't start until later.