for a start you could try not fucking up. no seriously, wtf do you expect us to answer? you gave us absolutely no information at all.
...few things I found out the hard way.... keep your electrical connections raised up off the floor, use zip ties to shorten ext cords. Buy a quality ballast, cheap generic ballasts can be unreliable. (the inside of mine overheated and melted, lucky it didn't catch) Wire your own sockets? Then it comes down to your skills and common sense.
Some people really do some dumb shit. A group of high school kids in my area (4?) Had a decent sized grow in a house and one of the kids misted the plants with the light on. He sprayed upward and it hit the light. It ended up busting and catching the whole house on fire. They all dipped and the parents got busted for it. The kids tried to admit to it later down the line, but they swore they were covering for the parents and felt there was no way they could set up a grow without the parents helping. Grow fires can start just use common sense.