Types of Fire ground photos:
Daytime:
Taking pictures in the daytime is easy. Try to vary your angles and vantage points. Use your zoom lens to capture the overall scene as you approach. Once at the fire you can focus on the fire itself. Look for hose lines going in the building, or outside ventilation being done. The possibilities are almost endless. Try to keep the sun at your back and always use the light to your advantage. If it is overcast or the smoke blocks the sun, consider using your flash, you will be surprised at how much it will brighten the scene. Every photographers shooting style is different, some like "smoke" pictures, some like only close-ups, but I always try to photograph the firefighters working with fire visible in the picture, I find that this is what most people want. Vary your pictures by turning your camera. Take the same shot vertically or horizontally you will be surprised at the different shots you can get. Take vertical shots of aerial apparatus in use to show height, or try to get above the fire in a adjoining building to look down on the scene. Always move around the scene if police and fire lines do not hinder you. DO NOT develop cement feet and stay in the same place and snapping shots every few minutes. Your pictures will not be that good. There WILL be a time when you will not be able to move around, but always try.
Night time:
Photographing fires at night requires that you use your flash. If you do not use a flash, all that you will record is flames, with not detail of the building or the firefighters around it. The other tips in the daytime tip apply here to. There are some neat things you can do at night without a flash called existing light shots. This is when you do not use your flash and use a slow shutter speed. Warning lights, headlights, and streetlights can transpose a dreary scene into one that is dramatic and colorful. Make sure that you stand to the side and do not shoot directly into the lights.
Before the fire:
Past experience shows that seconds count in fireground photography. You may only have to go a short distance to discover that the fire is out. It is also to arrive at a scene and discover that you only have 4 shots left on your camera with no more film. If the fire is still going good you will get a second chance by reloading, but if the firefighters are extinguishing the flames you will probably be out of luck. To make every second count, make sure you camera bag is always accessible and that every piece of equipment is ready to go. Your batteries are fresh, film is ready, and you remember how to use your stuff. Make sure your equipment is ready cause it can make the difference between a big disappointment and an exceptional shot.

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Below are three photos taken at night,
Photo one, of the photos was taken with no flash and back lights the firefighters.
Photo two, I beleve it was taken with a digital pocket camera, all the light comes from a full involvied house, this brings out some great detail and reflections.
Photo three, was taken with my large flash, other wise the fire ground was very dark, no fire ground lighting at that time. With out the flash the image would of never shown up.