Caravan vents should be left uncovered to provide adequate air circulation inside the caravan, however if your caravan is left in an exposed or salty location, the vents on the side of the prevailing wind can be closed off for winter. If you have regular access to your caravan you could place some moisture absorbing crystals (available in our shop) in cupboards, under beds, etc to reduce the risk of condensation, but these do require frequent changing. You could also put a low wattage heater in your caravan to minimise the damp and condensation. If possible remove the soft furnishings and store in a warm, dry place at home.
Walls and ceilings should be wiped over with a mild anti-bacterial solution eg. Dettox or something similar. Cupboards should be emptied, cleaned and vacuumed out. Small doors can be left ajar to assist ventilation, but larger doors should be closed as they can warp.