Moderately strong tea, milk in afterwards
Actually, it depends. I prefer loose leaf tea to tea bags (*), but I drink more bagged tea due to the convenience. Anyway, if you make a proper brew(**) you need to scald the pot, put in the leaves and then put in the boiling water. If you've faffed around for too long between starting and pouring in the water, boil it up again then put it in the pot. It needs to be boiling(**). Then put it on a hot stove for about 4-5 minutes. For this type of tea, you absolutely need to put the milk in the cups first, otherwise you scald the milk. You might not believe this, but do a blind taste test and I think you'll be able to tell the difference.
For bags, you also need boiling hot water to begin with (and you may also wish to scald the cup first so it stays hotter, but it's not necessary), but from that point on you just leave it to brew by itself for a couple of minutes. Personally, I give it a stir (usually by grabbing the back with my fingers and swirling it around, but you can be fancy and use a spoon) and remove the bag before adding the milk, but the other variations of this aren't wrong. The only thing I'd insist on is if you have to use a sweetener, then it has to be honey. Even then, sweetener is really only something you want after some kind of shock or a day's hard labour, in which case it's acceptable :)
* Barry's Tea is de rigeur; it's a blend, but mainly based on Assam (also called Breakfast Tea by many)
** Actually there are many "proper brews", but I'm talking about black (fermented) leaf tea here. That's not to say that things like green/gunpowder/matcha tea (which don't take kindly to boiling water at all), Oolong or even (horror of horrors) mugi cha (which actually isn't a "tea" at all) aren't all worthy beverages in their own right.
*** Incidentally, this is why it's hard to make a decent cup of black leaf tea at altitude since the boiling point is reduced. Green (unfermented) tea is much better there.