Not near the house
Make sure that your generator is not near your house, the noise for one can be a huge distraction and annoyance but the most important reason for this is so that there are no cases of Carbon Monoxide posining. These are combustion engines, which means it realeses carbon monoxide gas, so make sure it is no in or too close to the house.
Propane Beats Gas
This is one of those choices that is different per person, Gasoline is sometimes seen as the more common used one because it is cheaper and the generators that use gasoline are also cheaper. The one big difference between these two choices is that propane does not go off, you can store it for as long as you like without there being any problem when you use it in the future.
Fixed in your area
If you are ordering a generator from overseas or buying it from a friend, make sure that it can be fixed by someone in your area, if you land up having a problem with your generator and it is a foreign brand there can be large problems with fixing them, especially not in a rush.
Heavy Duty Extensiions
Another important thing to remember is that if your generator is outside then you will need the right type of extension for that type of job, heavy duty extensions may be expensive but they are worth it, one of the worst problems to deal with is a faulty connection to your generator because the wire wore down.