The only thing that should go into the grinder are reasonable quality coffee beans
that are not too cold. Beans that are straight out of the fridge or freezer will
have condensation on them which will clog the grinder, oily beans also cause blockages
due to their stickiness.
Avoid beans with any sort of coating on them.
Only adjust the grinder when it is actually grinding, so press a coffee button and turn the
adjustment knob a small amount, then make another couple of drinks to test the effect.
Don't have the grinder set any finer than you need to get a good crema on the coffee. As a general rule: when the used grounds in the bin are like round cakes that is fine enough.