My unrealistic advice is to use a straw. This avoids the dark liquid bathing your front teeth and then staining them.
BUUUUUUT? this is boring and unrealistic, especially if drinking hot coffee (iced coffee is doable 
).
I would say, instead of sipping on a coffee or two all morning, have your coffee in one sitting and then try to just stick with water for the other parts of the day.
If you are slowly sipping on it constantly then the time is sits on your teeth is longer and this will lead to more staining.
Bottom line is ? drink your damn coffee, be happy!
