When you cook with saffron, the most important flavouring substance in saffron comes from the saffranal, and it is important to dissolve this and all other substances in the liquid. Since most of the colouring and flavouring substances in saffron are water-soluble, it is advisable to pound the threads a little in a mortar and add some sugar or salt. Soak the threads in lukewarm water, milk, white wine, vinegar or a broth (no red wine containing tannins) and let the threads steep for as long as possible (30 minutes to 2 hours). The better the quality of the saffron, the longer it should be soaked. Ideally, let the saffron steep in the liquid overnight until the colour of the threads has faded. This ensures that all the ingredients are dissolved in the liquid. 
If you want it to be a little quicker, there is an alternative. Heat the saffron threads on a saucer in the oven at 40-45 °C for 4-5 minutes; higher temperatures or longer would destroy the aroma. Then add a pinch of zuker or salt and crush in a mortar. Dissolve the powder with some warm liquid and let it steep for 15 minutes. If you want colour and aroma in your dish, add some at the beginning and some towards the end of the cooking time. Use only porcelain, earthenware or glass mortars, but never metal ones as they are not good for saffron.
The saffron loses its aroma much faster as a powder than the whole threads. Since saffron is very expensive, there are many fakes on the market. The powder is often mixed with other spices, such as safflower or kurkuma. Therefore, do not buy saffron as a powder, but always in whole threads. This way you can be sure that it is really the stigmas of the saffron crocus and not some cheap substitute. Not everywhere that saffron is on the label is actually saffron on the inside. Saffron is a matter of trust!
Saffron quantities for 4 people.

1 sachet = mostly 0.1 or 0.2g
0.1g = about 40-50 original Sari saffron tips (with inferior saffron this can be less, but then you get a lot of the tasteless stalk parts).
knife tip = 20-30 freshly ground saffron tips
a bunch saffron threats on white background, cooking with saffron.
saffron flower on a white paper with 5 saffron threats
Saffron is as capricious as a diva. Only in the presence of friendly ingredients does it unfold its full aroma. Some things spur it on, others leave it cold. It unfolds its invigorating and harmonising effect best in milk drinks. It likes a flowery, sweet taste especially when accompanied by rose water. In liqueurs, it can have an intoxicating effect and make you laugh. With cardamom it tastes mild and gentle. With lots of lemon, it loses colour but retains its flavour potential. In the presence of vinegar, its colour becomes striking but the aroma weakens. White wine melts it and makes its aroma interesting and soft. It does not get along with tannic red wine.