Darjeeling is known as the champagne of teas. I often start the day with a brew of 2 parts Darjeeling and 1 part Lapsang Souchong. In days of yore when the tea caddy was one of the most important items in rich houses, with the key held only by the housekeeper, the caddy often had 2 compartments; one for china tea, one for indian. Guests were offered either, or a blend of the 2.

The debate about milk first or tea first has covered most ideas I've heard; one theory about pouring the tea in first was that posh people did it to show off how good the quality of their fine bone china was. Although thin enough to see through, if you could pour boiling tea straight into it without the cup cracking it proved your crockery was highly superior. People who put the milk in first were almost admitting that their cups were cheap. The flavour of the scalded milk seems a good reason to put the milk in first now people are not so bothered about showing off the quality of their cups. As Helen comments it definitely does affect the flavour. I too sometimes scald the milk before adding very strong coffee, about 1/2 & 1/2. It comes out like a cappuccino without the froth (although I usually take it black).

As to water, I live in a very hard water area and it makes disgusting tea. Until I moved to Devon for a couple of years and was able to drink the nectar that resulted from brewing tea with soft Dartmoor water I don't think I had ever tasted a decent cuppa. I now use a filter jug and only ever boil a kettle with filtered water. Not only does this mean I can make great tea, but the kettle no longer furs up with limescale. The aforementioned Taylors of Harrogate, makers of Yorkshire tea, now produce a hard water tea, I was given a box recently but haven't tried it; I'm reluctant to risk the limescale build up that results from even a couple of pots boiled with tap water.