The first rule of working on cars and using tools of any kind is don’t be stupid. Make sure personal protective gear – goggles, gloves, ear defenders, masks and a set of overalls - are hanging on a hook in your garage and use them wisely.
If you’re working with power tools, protective gear is essential. Never attempt to work under a car without supporting it securely using suitably strong axle stands. If you haven’t got a fire extinguisher, buy one and keep it near to hand. The bottom line? If you’re not completely confident of your own ability to complete any task safely, don’t even start it. Leave it to the experts.