I promised I'd be back to share the "Rock 'n' Roll" technique with you. So, go get out a round-ish stamp and come right back. I'm going to use the medium flower from the Greenhouse Garden 2-step stamp set (p. 94, 113824, $25.95).
You'll need two stamp pads, one a lighter color, the second, a darker color. Ink up your stamp with the lighter color. Then take it over to the darker stamp pad and just roll around gently on the outside edges of the image. You're done. Now stamp it on a piece of cardstock and you'll see that darker rim. Isn't that cool? And easy!?
You can also 'stamp off' your inked up image to get a light shade of your color: ink up your stamp and then stamp it two or three times on scrap paper. It will be several shades lighter than stamping directly from the stamp pad. Now, roll your stamp on the stamp pad, just inking up the outer edges. Finally, stamp it where you want on your finished (or practice) piece. In the case of this stamp from the Greenhouse Garden 2-Step stamp set, I also stamped the detail image in the Mambo Melon ink and then stamped it on top of the rock-n-rolled image. You can use your Stamp-a-ma-jig for perfect placement if you want. I just 'wing' it so my placement is not perfect.
It's not perfect placement as I said, but.....it doesn't usually matter. When it matters I definitely use my Stamp-a-ma-jig. You can click here for a tutorial I did on this tool.
Let me know if you have any questions about rock-n-roll or the stamp-a-ma-jig. I'll do my best to answer them.