Warm the pot!
+ Do not use round or, heaven forfend, tetrahedral bags
+ Wash the pot after use
+ Wash cup or mug after use
The making of tea and the ancillary actions is an essential alls-right-with-the-world chilling out time. Bag-in-a-mug merchants are too busy for their own good. I despise them.
Remember many 'acquired taste' teas don't have milk at all.