First, find a stamp that has a lot of surface space and not a lot of detail. The Medallion stamp worked great for this, but I can imagine flowers, etc. too.
After you stamp your card with Versamark ink, lay it down in your embossing tray. Take your first color of embossing powder and pour it in spots, then without tapping the first color off add another color in the same way. Then do it again with another color. Fill in the other empty areas until you have the whole stamped image covered THEN tap off your powder. BEWARE - it will mix. And that's up to you what you want to do with it. You could save the mixed powder to use at a different time, or just pitch it. I'll save mine - you never know what it will look like on another project.
I have a friend with a Birthday this weekend that I was planning to send this to - I hope she likes it! ;)