Wear safety glasses to protect from debris of fireworks.
Have a bucket of water and a mop or fire extinguisher handy to put out fires quickly.
Tape your cakes together to prevent them from falling over. Taping cakes of similar size is best.
Screw down artillery shells or put them in a concrete block to prevent them from tipping over.
Use a plastic cup with a hole in the bottom to put a sparkler through and use to protect hands from the sparks.