Well, what's popular to do is invite friends and family over (or go to someone else's house) and have a barbeque cookout. Then later you can go watch the city's fireworks show or do a little one of your own. Last night we just went in town to watch them. But a few times when I was little we would go to my grandmother's house and me and my cousins would light sparklers, fire crackers, Morning Glorys, etc...all that fizzly stuff, and sometimes my uncle would bring some fireworks and set them off in the back yard.
Oh, and a few years ago me and my dad would park on a country road behind the park where a different nearby city's firework show was going off and watch it from there (it'd be too hard to find a place to sit at the park, because it gets really packed at that show.) Their show is called Big Bang Boom, and it's where they have awesome fireworks coordinated to the songs a local radio station would play. They normally play popular rock songs, but one year they did all partiotic songs.
I remember one of the coolest things they did one time was when they were playing the song "Shot Through the Heart" by Bon Jovi, and it hit the chorus, they sent up a red firework that burst into the outline of a heart, and then a little yellow one fizzled through it like a bullet.