First of all, cleaning is the key. Many times on a home inspection I will notice that the dryer vent is dirty and someone will say "That needs to be cleaned!". Unfortunately, that is usually when we arrange to clean the vent - when it is already overly dirty. Make a maintenance schedule to clean your dyer vent every few months (depending on use).
Also, make sure that the dryer vent head is free of plants and other obstructions. Having a dryer that vents into a bush or under a deck does not help the situation.
Questions? Contact me!