Use fresh water from a kettle. Water left in the kettle loses vitality and makes tea taste dull. Rinse the pot with boiling water to bring out the tea's flavour.
Add 3-4 teaspoons of tea to a 6-cup pot. Pour in boiling water and leave to brew for 3-4 minutes. Pour through a strainer & add milk or lemon.
Whether you add milk before or after is open to debate.