Some houses suffer from window condensation more than others and it is generally due to ventilation. Rooms that tend to have higher levels of condensation are the kitchen and bathrooms, due to the increased level of moisture in the air.
Condensation build-up can be reduced in the kitchen by making sure the room is well ventilated, having the extractor fan on at all times while cooking, and not leaving warm foods on the counter top to cool down.
The same rule applies in your bathroom, use of an extractor fan helps largely in the reduction of condensation, and of course keeping windows open when possible. Also, hanging wet clothes outside, rather than inside will help reduce the moisture levels in the air.
A build-up of condensation around your windows can cause other problems such as mould. If the issue continues you may want to consider investing in new windows for your home or getting a professional to assess your homes insulation status.