Getting a good fireworks photo really comes down to two important factors, preparation and luck. I don't think I need to elaborate on the luck part, so I will just focus on what preparation should be done to make sure you get the photo you want!
1. Research
Location
It is very important to do your research to find the vantage point you want, this shouldn't be too hard since everyone knows where are the popular spots around town, so just check those out online and see if you can find some photos that you like and that will be your starting point. This will be the most important part of your photo because your vantage point basically determines what your photos are going to look like. Check it out beforehand if you have time, if you don't, try to be there as early as possible. It is going to be a long wait, but it might be well worth it to get a great photo!
2. Gear
As much as we photographers love to carry tons of gear to cover all possible situation, I would NOT recommend bringing too much because it is most likely going to be very crowded and you are just going to make it difficult for yourself. Bring only what you need!
Camera & Lens
Last year I only have an 18-200 with a D300, so I didn't have much of a choice. With that being said, it still covered basically everything I need. I do prefer zoom for this occasion as it provides the flexibility as you probably will be stuck in a crowd at the end of the day. If you know exactly where the fireworks are going to be, bring the appropriate focal length for the best results, but if not, stay on the wider side to make sure you get more than you need, nothing worse than getting the exposure right but with half the fireworks cut off.
Tripod
Tripod is a must! Bring your tallest and sturdiest tripod so you can shoot above everyone when you need to. Be careful not to take up walkways or create any tripping hazard for others, be considerate is the key (last thing you want is someone blocking your view because you pissed them off!).
Remote Shutter
A remote shutter, wired or wireless, will be very useful as you don't have to worry about any camera shake and it allows you to enjoy the fireworks a little bit more without the need to stay behind the camera!
Memory Cards & Batteries
Bring more than enough of these to make sure you won't run out!
Food & Water & other important stuff
It is not just about camera gear! Bring a chair, some food and drinks and preferably a few friends to make the long wait more bearable!