Here is a quick card I made up for our youngest daughter's birthday. My color combination came from the small piece of ribbon I wanted to use on the card. Because the buttercup piece of cardstock was too plain on it's own, I used a background stamp to give it some dimension. This particular stamp set is no longer available, but you can create a background with any of your stamps.
I didn't have any little colored flowers other than the green one, so I inked some white daisy flowers from CTMH. They are a fantastic deal and so versatile. Buy them here. Not much else to tell except that she loved all the pretty colors.