Identify whether you need iceberg lettuce for crunch (fresh salads/wraps) or bulk (toppings).
Choose the substitute that matches your texture goal: romaine/green leaf for similar bite, cabbage/celery for extra crunch.
Use the listed ratio by weight or volume, then cut smaller if your substitute is tougher or thicker.
If your substitute is stronger or can turn bitter (like cabbage), salt briefly, then rinse and drain before serving.
Dress lightly and serve immediately when using tender substitutes (butter lettuce) to prevent collapse.