Empty your kettle, then fill it with freshly drawn water from the cold tap. Put the kettle on. Just before it comes to the boil, pour a generous dash of the hot water into your teapot (glazed china or earthenware, by preference), swirling it round and round inside the pot before pouring it away. Warming the pot is not a meaningless ritual, but ensures that the water stays at boiling point when it hits the tea, encouraging the proper opening of the leaves.
Dole out one heaped teaspoon of tealeaves for each person, and one for the pot, straight into the warmed teapot. (Large-leafed teas -- such as jasmine -- are comparatively light for their volume, so add an extra spoon or so of these.) The kettle will have reached a galloping boil by this time, so pour the water over the tea. Take care that the water is not long boiling; over-boiled water loses its oxygen and results in a bitter, muddy brew of tea.
Allow the tea to stand and brew for anything from three to six minutes, according to the leaf size (less time for small leaves, more for large ones). Give the tea a good stir, and pour, using a strainer to catch leaves. If you take your tea with milk, you should add it to the cup, cold and fresh, before pouring the tea. (P.S. Tea bags are never a good idea. The tea they produce is simply not the same.)