In the store, look for crisp, bright leaves.
For maximum freshness, wrap washed green leaf lettuce loosely in paper towels and store in the fridge in a large, sealed plastic bag or other airtight container.
Prior to consumption, remove leaves from the core, fill sink with cold water and submerge leaves to wash. Rinse leaves in cold running water to remove any remaining soil. Pat dry to remove excess moisture or use a salad spinner.
Green leaf lettuce is high in vitamin A and other antioxidants and is also a great source of folate.