Condensation in homes occurs when the interior atmosphere gets out of balance and is holding too much water vapour and humidity levels remain high for long periods.
An inspection will identify the primary action areas after which further measures may be necessary.
The most common wall/ceilings affected by black mould due to condensation are typically your bathrooms, kitchen and bedroom walls are often susceptible to black mould growth.
Brief Action plan
To minimise condensation occurring maintain the ambient temperature above 15oC and ideally between 18-21oC, avoid heating the property for short periods as this will reduce its moisture buffering ability. When showering or bathing keep the door shut and the area warm and ventilated until it dry, avoid drying clothes within the building, if you have to, keep them in one room, which is heated and ventilated. A dehumidifier may be of help if you are unable to ventilate.