Wooden kayaks are generally extremely weather resistant and durable, so if you simply follow good practice and avoid major damage, no special precautions have to be taken compared with maintenance of kayaks in other materials such as plastic or kevlar and fibreglass or carbon fibre.
Salt water does not damage the lacquer, but rinsing with fresh water is recommended.
Best to wash and dry after use. Store the kayak or canoe with the deck facing up – condensed water in the boat will then be able to evaporate.
Cover minor scratches in the lacquer with epoxy glue or lacquer.
Read about minor repairs.