Easiest thing to do is improve ventilation if you can. Ensure no air bricks are bunged up. If you can, open a window slightly (especially if its a small window above a main one). The other big cause is gas fires, especially if they are 'stand alone' fires (not built into the fireplace). Gas fires produce a lot of moisture, so cut down on these if you can.
Invest in a dehumidifier - excess moisture in the air is literally sucked out. We were amazed at how much water was in the container after using ours. We use it now and again and it certainly kept condensation down to a minimum.
As already said, not heating at all (or letting all the heat out) or dehumidifying are two methods. There are other ways to reduce the condensation but it is essential to know what causes it. Naked flame heating is one possible reason because the heat is so unevenly distributed. Air trapped behind curtains is another accelerator, especially if single glazing is involved. Unvented cooking steam (no exhaust fan) can cause condensation in other rooms. A more or less permanent solution for most cases is central heating radiators positioned directly below windows that are double glazed and where curtains allow flow of air over the full height of the window. Use the heating to maintain a temperature with little variation day and night and you can enjoy it without side effects. Too little (or infrequent) heating is very often the cause, and cold houses need a lot of ventilation but will closely follow outdoor temperatures.
You could also reduce condensation by not drying wet clothes on radiators. Having extractor fans in your kitchen and bathroom. Or moving your washing machine/dryer to the garage.