Some of my Tiffany silver suffers a little tarnishing, it's mainly due to an individuals acidity level in the skin, I don't really have any trouble with the bold smooth items like my bone cuff or Orchid earrings, but my more fiddly items do, like the heart link necklace. 
However, I could not live without this;
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=380041228962
It's a pinky paste that lathers up like soap, you use the sponge pad to 'shampoo' your item, it takes 2 mins to do, run the jewellery under the tap and hey presto! Just like new, can't recommend it highly enough.

However, I could not live without this;
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=380041228962
It's a pinky paste that lathers up like soap, you use the sponge pad to 'shampoo' your item, it takes 2 mins to do, run the jewellery under the tap and hey presto! Just like new, can't recommend it highly enough.
