It is very important to keep your filters clean as any kind of obstruction will decrease the amount of air the system can take in, also increasing the amount of electricity needed to cool the room. It would be best if you cleaned your filter once every two weeks by washing it with water or running a vacuum cleaner over it.
If you find your filter to be overly dirty, wash it in lukewarm water with detergent and leave it to dry (avoid direct sunlight though). Some models may have an automatic cleaning function which can be activated to clean the filter. It’s also a good idea to clean the cooling fan to help keep electricity consumption low.