As others have already said – green tea is far better in whole leaf form than the powdered stuff you get in bags, which is just a complete waste of money and you can usually taste the bag more than the tea!
The Tea Pigs Mao Feng is quite easy to get hold of and comes highly recommended.
If you really want to make the brewing easy, just cover the bag in a bit of cold water first and then pour on the boiling water. But definitely avoid the cheap stuff in bags – and the flavoured novelty teas – basically anything you can buy at the supermarket!
White tea is really nice, but has a very subtle flavour – I find that it sometimes needs to be 3-4 times as strong as recommended to get the flavour coming through.
Yerba mate – now there’s a acquired taste – still got a packet I never managed to finish off in the back of my tea cupboard, the flavour is terrible at first but on the plus side it does tend to leave you feeling a little bit high.