Field Selection - Darker colors mean more grain and slower harvesting.
Driving - Arrow keys, tap is better than hold for this one.
Manifold Pressure - How quickly your putting grain through the machine. Too fast and it will choke.
Grain Level - When it's full, time to unload.
Unloading - Pull the combine along side the truck with the auger out. Auger over truck will unload.
Scoring - Grain only counts if it's on the truck. You should be unloading when the timer expires.