A popular site for fireworks information is
NYIP. A google search for fireworks photography will give you much information. Here are some hints in addition to the NYIP article.
The Jim Jones rule for exposure when shooting slides is to set the aperture to about the square root of the ISO rating. Long ago I shot a lot of fireworks on Kodachrome 25 at f/5.6. Daylight transparancy film gives good results. Film faster than ISO 100 has little advantage in shooting fireworks. For color print film I'd open up a stop over the square root setting. For black & white open up two stops. Light meters are useless for fireworks. Exposure of fireworks isn't critical, as long as the shot isn't underexposed. This rarely happens. Major fireworks displays might require a smaller aperture than I've recommended. Some one-hour printers may have a problem with fireworks, so evaluate the negatives rather than the prints.
In small town displays I usually leave the shutter open for many bursts. The maximum time is usually determined by the brightness of the sky. The exposure can be long enough for the sky illumination to barely expose the film. A little skylight in the image helps define any horizon or foreground. Remember, the sky may brighten during the exposure due to the accumulation of smoke, or darken as twilight deepens.
Using a sturdy tripod is helpful. Contrary to what NYIP said, mirror lock-up has little advantage in shooting fireworks. Some people may even like the squiggley trails of fire from a hand-held camera. Holding the camera very tightly may induce more tremors than normal relaxed hand-holding. Try it for at least one shot.
Try to find a site with no bright lights on the ground beneath the display. Fireworks reflected in water can be beautiful. This also eliminates some distracting foreground and lights. If you are at the edge of the water, people can't get in front of the camera. Shooting from a distance can reduce problems with a crowd and give you more control over the fixed lights on the ground. It may also let you make a fast get-away to avoid the traffic jam after major fireworks displays. Since it is impractical to frame every burst just right, set the camera so it includes most of the sky where the fireworks are displayed.
Capping the lens between bursts reduces the sky glow in the picture. I prefer a piece of black cardboard maybe the size of a sheet of typing paper. This can also be used to block bright lights on the ground. When this is done, keep the cardboard moving slightly to eliminate a recognizable boundary between the blocked and unblocked areas. One can usually hear the propelling charge and see a spark rising into the sky. Keep the lens capped until you are sure that it will be a photogenic burst, not merely a distracting blob of bright light from a bursting charge. When the display fades, recap the lens and wait for the next one. In a large display, there may be no wait. When you think you might have a nice grouping of bursts, cap the lens, advance the film, and try again. Fireworks photography is chancy, so shoot lots of film.
