I started off using white glossy paper for the roses and followed the watercolor splash technique you can find on most Stampin' Up demonstrator websites, but then I found the paper got soggy with so much water on it and decided to switch paper to heavy watercolor paper. I also found that if you just use distress ink pads and swipe one on your craft mat, spritz it with water slightly, then use a brush and paint over your entire rose with it, it works much better than the splash technique, for me anyways. To get the darker color, I just used distress ink on the craft mat without spritzing it with water, and brushed it on with a very fine paint brush. The rose is heat embossed with white powder.
I haven't stamped greetings on the cards yet; I usually wait until I need a card for a certain occasion then stamp it appropriately.