If you take one technique away from everything written about saffron, make it this: bloom it first, and add it late. Almost every disappointing saffron dish has got one of those two wrong.
Blooming first. Saffron keeps what it has inside dry threads, and a dry thread dropped into a pot releases very little of it. What you want is the colour and aroma moved into a liquid, where they can then spread evenly through everything else.
The method is unceremonious. Warm — not boil — a few spoonfuls of milk or water. Add the threads. Leave them ten to twenty minutes. The liquid turns a clear, deep gold and smells strongly of saffron. That liquid, threads and all, goes into the dish.
Two details worth getting right. Warm, not boiling: very hot liquid drives off aroma at the same time as it extracts it. And give it the time — five minutes gets you some of the colour and not much of the smell. If you are cooking something that takes an hour anyway, bloom the saffron at the start and let it sit while the rest happens.
Milk or water is largely a matter of the dish. Milk is traditional for sweets and gives a rounder result; water is better where milk would be wrong, and in a savoury rice it is usually the right call.
Adding it late. The aroma compound in saffron is volatile — it evaporates. Heat it long enough and it is gone, and you are left holding the colour, which is the cheap part and the part a substitute could have given you.
So saffron goes in near the end. For a kheer, stir the bloomed liquid through in the final few minutes rather than letting it simmer for half an hour. For a pulao or biryani, pour it over at the finish, or layer it in just before the final dum. For milk it is the whole point of the drink: bloom in a little, add the rest, and do not boil it afterwards.
There is one legitimate exception. If a dish needs saffron's colour to penetrate something — rice, for instance, where you want individual grains tinted rather than a gold sauce around them — then the bloomed liquid should go in early enough to be absorbed. You lose some aroma and gain even colour. That is a trade, made deliberately.
The reason this matters more than quantity is simple. Doubling the threads in a dish that boils for forty minutes gets you a slightly deeper yellow and very little else, at twice the cost. Blooming half as much saffron properly and adding it at the end gets you the smell — which is what anyone at the table will actually notice.
