I've been trying out this technique today, after seeing it online a while ago, and finally getting the tissue in the UK, which I'm selling in my online shop Opal Crafts.
All stamps used are from Visible Image, also available in my shop, but they're selling fast, need to get more!!! This technique is nice and easy, all you do is place your pieces of tissue on your card and wet it. I cut some circles with a die, but you can tear it too. You can also use the same wet piece a few times, it's just that the colour isn't as bright. Each of these samples uses just 2 shades of each colour, but as they bleed into each other, the colours change.