1-Clean the lint screen/filter before or after each load of clothes. If clothing is still damp at the end of a typical drying cycle, this may be a sign that the lint screen or the exhaust duct is blocked.
2-Replace foil accordion-type ducting material with rigid or corrugated semi-rigid metal duct. Most manufacturers specify the use of a rigid or corrugated semi-rigid metal duct, which provides maximum airflow. The flexible plastic type duct can more easily trap lint and is more susceptible to kinks or crushing, which can greatly reduce airflow.
3-Clean the dryer vent and exhaust duct every one to three years depending on dryer usage and overall length of ductwork. The longer the dryer ducting the more frequently they should be cleaned, because air flow is reduced in longer runs of ductwork causing more build-up of lint. Check the outside dryer vent while the dryer is operating to make sure exhaust air is escaping. If it is not, the vent or the exhaust duct may be blocked.