Use the correct units for every problem. Forgetting to label your answer or using the incorrect units is a sure-fire way to miss easy points. To make sure you get full credit for whatever problem you're doing, be sure to label your answer with its correct units based on the type of information being expressed. Some of the most commonly-used units for common measurements in physics are listed below — note that, as a general rule, physics problems almost always use metric/SI measurements:
Mass: Grams or kilograms
Force: Newtons
Velocity: meters/second (sometimes kilometers/hour)
Acceleration meters/second2
Energy/Work: Joules or kilojoules
Power: Watts