I love fireworks and there are three MASSIVE fireworks warehouses nearby. Over the years I have seen a lot of crazy stuff happen and ruin what should be fun days, so here are some basic rules that I follow:
My number one rule is no more rockets ever. I have seen too much crazy crap happen. Once I lit off a huge oversized bottle rocket with an explosive that could be heard for a mile away using a PVC launcher that I built to ensure accuracy. That thing lifted off and got about 20 feet off the ground, made a 90 degree turn and headed down the block 100+ yards and detonated on the ground in the middle of a bunch of young kids. No one was hurt, but my neighbor hates me to this day. I have seen a lot of other stuff like this over the years - especially when people don't have proper launchers. My neighbor exploded a rocket on my roof and a couple feet in the other direction would have ignited the pine needles in my gutters.
My number two rule and the solution to number one is to always use mortars for aerial displays instead of rockets
Rule number three is to modify the mortar launchers by attaching them firmly to a 2x2 foot piece of 1/2 inch plywood so they physically cannot tip over. The mortars they sell these days are ridiculous and awesome at the same time. Last thing you want is one of them exploding anywhere but 100+ feet over head. My friend's next door neighbor burned down his new detached garage last July 4th because the mortar tube fell over in the grass after the fuse was lit. He apparently also went to the ER with some burns from trying to put out the fire.
Rule number four is that mortar tubes wear out and are rated for the ammo it comes with. Use the tube only with the ammo that it actually comes with and discard the tube when the ammo is gone. The tube might last years but on the other hand, I have seen them explode and the projectile stayed dangerously low and off target
Rule number five is safety glasses, fire extinguisher, hose, keep people back at a safe distance and other common sense stuff.
Rule number six is little or no alcohol for the person lighting the fuses.
Rule number seven is to remember that these things are built in China by 3rd graders. Never, ever trust them to work as expected, expect them to shoot fireballs at anyone nearby and always be really careful with duds. Flood duds with water from a hose if possible or wait for a really stupid long time before getting near.
Finally I will say "just say no" to letting your kids be anything other than distant observers and make sure they see you treating the fireworks with ultimate care.