Write an article based on this "Turn off the power. Remove the fan."
Before you do anything else, ensure that the fan is turned off and cannot turn back on until you are finished cleaning it. Most models will have a plug that is located directly behind the cover. You could remove the cover first and unplug the fan, but just to be safe, go and temporarily pull the breaker for your bathroom. The fan is now safe to work on. Unscrew the assembly that is holding the fan in place, then very gently remove the fan. Be careful not to drop the fan or hit it on the side of the exhaust pipe as that could potentially chip the fan blades. Broken fan blades will cause the fan to be louder and less effective.