Jim Lad said 'Then there's the usual fridges, computers, light bulbs fans and flatulence.'

Setting aside the flatulence, he is talking about this: the various hums, rattles and clicks of the house turn into the hiss on a recording. So turn the fridge up, the furnace down, the fans off. Set your mic as far from other noisemakers (including the fan on your computer) as you can.

In my house, it is essential to stop the cuckoo clock.