When brewing tea it is essential that the water be at a boil before adding the tea.
Not "warm", not "hot": boiling.
"Looks warm enough" doesn't cut it. If the water isn't bubbling, it isn't hot enough.
Oh, and if you're making a cuppa with a tea bag (nothing wrong with that, and my preferred method these days), the milk goes into the cup before the boiling water. Scalded milk just ruins the whole experience.
That is all.