Identify your dish’s broth role: soup for body, sauce/gravy for richness, or braise for flavor transfer.
Choose the closest substitute from the list, then use the listed ratio (start slightly lighter on salt).
If your substitute is reduced/concentrated (base, bouillon, miso), dilute to match broth strength before adding to the dish.
Simmer (or warm) just long enough to blend flavors; finish by tasting and adjusting salt/umami.
If the flavor feels thin, add one small boost: a pinch of salt, a small drizzle of oil, or a tiny splash of soy/worcestershire.