In the US Independence day or the night before can always be marked in the calendar if you want to take pictures of fireworks.
Going out early to find an unobstructed vantage point is essential. You don't want to be within a big crowd and because of longer exposure times the camera needs to be on a stabile tripod. I always dial in the long-exposure noise reduction mode. My Nikon D200 does not handle higher ISO values very well, so I leave it at ISO 100 and extend the exposure time as needed. With a newer camera you might be able to crank up the ISO value a little more without producing grainy and noisy pictures. I tried different combinations of exposure times and f-stops. For the most part the pictures turned out good with the camera set to 5-6 seconds and f8-f11. However, the image shown here is a little out of this range. We were just near a small town in Iowa and the fireworks is probably not as gigantic as in some of the bigger cities. In order to catch multiple fireworks explosions in one frame I had set the f-stop to 16 and extended the exposure time to 13 seconds.
Did I mention we had a lot of fun? In any case, please let me know what your experience with this kind of photography is. The next opportunity will certainly arrive soon.