I use Janina, which is good but toothpaste won't radically change the colour of your teeth. The best way (spent aaages researching it) is to go to a proper dentist and get plastic teeth trays specially made; the dentist sells you bleach which you put in the tray and wear overnight for 2 weeks. You then keep the trays and re-do whenever you feel like it. It has worked brilliantly, and has helped my confidence no end. DH is going to do it too, as is my mother.
It cost about £300 for the trays and bleach, and the refills cost £20 a time. So pricey but oh so worth it.
I bought Blanx at Superdrug while on the hunt for MUA makeup ( see other thread). It was half price so thought I would give it a shot, it has got rid of some light tannin staining nothing too obvious but it is early days.. I can recommend Crest whitening strips, they are not available in the UK but can be bought on Ebay.