Anticipate the action: Research when the show begins, ends, and how high the fireworks will be. Secure an unobstructed view by arriving early, and then consider the background and foreground of your shot. Try different zooms or interchangeable lenses, and experiment with buildings to give scale and anchor to your shots. Use the first few bursts to finalize your lens, focal length and framing.
Let the fireworks do the moving: You'll need a long shutter speed and a perfectly steady camera. If you have a tripod, use it!
No tripod? Find a solid surface at head or waist height with an unobstructed view. Use something soft to balance your camera. A Ziploc bag filled with beans or rice will hold your camera steady once you've pressed it down firmly.
Shoot for a long exposure: Fireworks take a second or two to burst, so leave your camera's shutter open for that long. If possible, choose T mode (shutter stays open until you press the release twice). Alternatively, choose B mode (shutter stays open for as long as you hold the release). Avoid camera shake by pressing gently and holding your finger steady, or use a remote release cable. If all else fails, try your self-timer!
Control the exposure: Control the brightness of the fireworks by setting your aperture. If it's too wide (ƒ2.
you'll lose the rich color, so start with a setting like ƒ8. Use the very beginning of the show to review your results. Focus? Use infinity.
Avoid flashes: Not only will a flash not reach that far, but the fireworks are the lighting! Turn off your flash.
Keep your ISO low: There will be plenty of light from the fireworks, so keep the ISO low (such as ISO 100) and you'll avoid a noisy image that may spoil the fireworks' brilliant effect.
Think about focal length: If you want the fireworks to fill the frame, consider how close you are. You already made a guess on framing, but be prepared to re-adjust your zoom or fit a different lens. Try a wide-angle if you're close.
Pay attention to firework frequency and variety: Leave your shutter open from just before the burst until just after. Once you know the burst height, watch the ascending trail to know when to press the shutter release.
Get ready for the finale! You'll need to widen your lens focal length and point the camera higher to get several bursts into one shot!