A serious issue that many understand, still must be stated. Do not run your generator inside your house or garage. having a generator inside can be a serious health hazard due to the fact that these machines put off carbon monoxide. The same as a running car in a closed garage. The Carbon monoxide is an odorless and colorless gas when at the right levels can be fatal within five minutes. So the golden rule is to never run indoors.
Typically when someone runs a generator, the weather is nasty and they lost electricity. Water and electricity do not mix well. It is best if it is covered by a tent like structure of some nature. If there is no cover then the chances of it blowing a fuse or even exploding drastically rise.
Adding fuel into a hot generator can be a very serious issue. When pouring fuel while the generator is hot can make it burst into flames. If a drop hits the engine then it will ignite and quickly get to the tank for the rest of the fuel that you were adding. To be safe, wait fifteen minutes and then fill it up.
Making sure that the generator is level can be one of the keys to success for having a generator last. If the surface is not flat then there is a chance that part of the engine will not lubricate. The engine not being lubricated can cause failure or be a possible hazard. This should play a major factor of choosing where to put it.
Having the right wattage being powered from the generator can prevent frying electronics or failure to power fully. A good generator can put out a lot of electricity and not knowing how much that is can harm the generator or appliances within the household. Good Heavy duty extension are also vital for the same reasons.