Warm air can hold much more moisture than cold air - when warm wet air comes into contact with a cold surface the water condenses out onto the cold surface - eventually droplets form - the dampness eventually leads to the formation of mould.
Keep the air a little cooler if you can
keep the steam levels down and open a window when bathing or cooking - even when it's cold
Ventilate whenever possible
Insulate - keep the warm air away from the cold surfaces
When you see condensation (on windows when you wake for instance) get into the habit of wiping it up
Keep wet clothes, shoes, coats, dogs etc outside.
Peccavi
November 2009