when picking fresh lettuce how do you crisp?

After you wash it, lay it in as close to one layer as you can, on several layers of paper towels. Roll it up loosely like a sausage. Store it in an unsealed plastic bag in the crisper drawer of your fridge. It should stay crisp for several days this way.

Best to pick it in the morning, assuming it's been well watered- it'll be at it's crispest then, especially in summer. You'll need to wash it anyway, so a bowl of cold water will do it.

If it’s baby lettuce, it likely won’t crisp. It’s very tender, and not meant to be crisp.

If it’s mature or head lettuce, soak it in ice water for about 5 minutes, then put it through a salad spinner so you don’t water down your dressing.