So in typical fashion I am posting a "how to shoot fireworks" blog a few days after the 4th of July... pretty useful right?!?! LOL
Sorry about that.. I just don't think of these things until after the fact.
My approach to fireworks is similar to waterfalls... and that is to use longer exposures to capture the motion of the subject. With a waterfall you will see a nice sheet of water as opposed to water droplets frozen in mid air (although those shots are also nice too when zoomed in real close to capture all the details... its just a stylistic choice). With fireworks you will see a bright light trail, and hopefully multiple complementary bursts which create a nice composite image.
My go-to exposure setting is M 1", f16, ISO 200. With that you get a nearly black sky, and capture a nice trail. I have used 1/2" as well with the appropriate change in f-stop. Tripods are mandatory obviously, as well as a wired remote release. I normally set it up with a wide focal length pointed at the scene of action. I always end up cropping things down (22MP FF to work with anyway...) so it don't matter too much to compose it perfectly then and there. One other thing to do is pre-focus the camera and then once set, switch the lens to manual. This will avoid those silly delays with the camera re-focusing (if it even can given there will be very little contrast to use). If your camera has it definitely turn on the long exposure noise reduction. With Canon this will effectively double your shot to shot delay but at 1" that matters little.. (now when I am doing night photography with a 2 stop ND filter and use 15 minute exposures... yeah then it matters much LOL). I have no idea if Nikon offers this feature or what it does..
So once all that is ready you just sit and wait.. I try to time my first shots with the launch of the rockets. Remember the camera will capture 1 seconds worth of action each time.. After the first shot i just bang away on the shutter button and hope for the best... you end up with a ton of throw-aways but it's effective.
Post processing wise there isn't much to do. Raise the saturation just a bit, and slightly raise the black point to really make that color pop.. add some sharpening (but not tooo much), and a bit of clarity. Crop it down the way you want to present it and then you are good to go. Obviously I am shooting in RAW mode here (and you should be too), and using ACR to process (ditto).
You can see some of my work from a few days ago on my new Fireworks gallery