When you need to boil something, cover the pots with something to disallow the vapours from collecting on the walls.
When taking a bath, make sure you turn on the ventilation far, and after finishing the bath, do not forget to close the door. It can take about 20 minutes after the shower to get rid of all the vapours inside the bathroom.
Never ever hang wet clothes inside your home to dry, as during the drying process, they produce vapours that can easily be collected onto the walls and cause damp.
Install ceiling fans in all the rooms and also exhaust fans in bathrooms and kitchen.
Control the home temperature and heat your home above 63 degree Fahrenheit to discourage condensation process. Another thing you can do to get rid of the damp walls is installation of dehumidifier in your home which can help a lot.
Install double or triple glazed windows in your home as they can help keep your home warmer, and eventually discourage the condensation process.