Try a small amount of honey, I drink a fair amount of tea (I'm English, it has to be done) and I'm one of those freaks who like it pretty stewed but if I go too far I find a drop of honey takes a lot of the edge of the bitterness.
Mate doesn't suffer from this inconvenience. I just pour the water and forget about it, refilling it when there's no more of that sweet liquid and tossing in more leaves when that liquid is no longer sweet.
Edit: that being said, your tip about adding a drop of honey is spot on! I also like my tea a bit overstewed and adding a splash of honey does take the edge of a little if I push it too far.
To be fair it's not quite right anymore: http://www.wolframalpha.com/input/?i=british+coffee+vs+tea