No matter where you are at, whether in a studio or some sort of outdoor location, it is best to turn off as many machines as you possibly can. This means turn off fans, appliances, computers, and anything else that creates a consistent hum or sound pattern. These sounds will inevitably show up in your audio and this is a simple thing you can do to get rid of it. If you are indoors make sure that all windows are shut and secured tightly to cut down on the amount of outside noise that gets in.