Don't know if anyone else notices this, before going out for shooting I check the lenses & filters for cleanliness, they look good.
When after spending the day out I notice most of the pictures have small black/ grey dots on them, obvious the lens/ filter isn't as clean as I first thought.
1st  ..........Whats best to clean the lenses & filters
2nd ..........Just keeping the lens cap on is not enough to keep the dust out, what is

Stuart