This is one of the most important yogurt-making tips. Leave the milk to cool down until you can dip a finger into the milk without discomfort.
You can buy a starter or just use some shop-bought plain natural yogurt. Check the labels and make sure it doesn’t contain sweeteners.
You can also cover it with cling film. Yogurt culture needs oxygenless conditions to work. Put the container in a warm place and leave for 5 to 6 hours.