invest in a small home use pressure washer to keep it clean and free of any growth.
Periodically replace any areas that are chipping, curling, and breaking.
Go to Sherwin William's and read about a product called Woodscapes, its an application that soaks in and used for just this case. Comes in any color you want or even clear.
We use it down here and its great, it has to be applied with a spray rig though. Its hard to paint cedar because of its roughness and its absorbancy.