I use a tripod ... manual focus ... white balance auto ... flash off ... lens Nikkor 28-80 mm zoom usually at 28mm on a Nikon D50 ...exposure mode is manual, Bulb mode ... ISO wasn't recorded but I would think 200 ... aperture f8.
No option for cable release and I would have to check, but if memory serves correctly my remote only works from the front ... so have to carefully push and hold shutter release ... not good, cable release would be much better if possible.
Basically I set up back a ways from the crowd ... main technique ... don't really use the view finder while actually shooting, just observe over the camera ... when I think something is coming ... using best guess, open shutter until I think I have something ... close shutter.
By using "bulb" I have a better chance of not missing something ... I let the fireworks 'paint' the picture rather than try to time it perfectly. If I'm a second or two early, with a dark sky, not much happens on your exposure before the fireworks explode. Most of the time my reaction is triggered by the rocket going up.
Time on shots below are 4.6 s; 1/3rd s; 5.1 s and 1.7 s
Get a lot of duds, but that's the joy of digital ... "film" costs are minimal.
Shoot and shoot some more. ;D
Howard