When you buy lettuce and other leafy greens early in the week, clean and refrigerate until ready to toss in a salad or layer on a sandwich.
To keep lettuce and other greens fresher longer, wash and dry them thoroughly before storing. Wrap greens in paper towels, then place in resealable plastic bags. Seal the bags tight, and keep in the vegetable crisper. Check the bags during the week, replacing any damp towels with dry ones.