Take care when handling and storing them. Never carry them loose in your pockets. Flashbulbs are incendiary devices, treat them as such.
Flashbulbs get VERY hot when fired.
Be careful when removing used bulbs from firers. If using a bulb and battery firing method, make sure your fingers are well away from the glass when you fire the bulb. If a bulb does shatter, pick up the bits of glass carefully. Be careful using flashbulbs with slaved flash. Misfires are likely if you are using sensitive slaves.