Knitting-N-Crochet.com, Knitting-Crochet.com, Sugar Tart Crafts and Yarnspirations are some organizations that offer good single crochet ripple afghan patterns. All of these patterns are freely accessible and are ideal blanket projects for beginners.
Knitting-N-Crochet.com has a simple baby ripple afghan pattern with instructions for a doll- or preemie-size blanket as well as standard newborn size. Detailed instructions for the single crochet afghan stitch accompany the pattern, along with photos of each step.
The pattern found at Knitting-Crochet.com is a reprint of a clipping from a vintage craft magazine. The blanket features rose and green hues, and it is made using single crochet stitches and a back-loops-only technique.
Sugar Tart Crafts offers a pattern for an oversized baby afghan in blue with a ripple pattern. The blanket features stripes of various sizes and is almost big enough for an adult. The author describes how to adjust the pattern to make a smaller afghan.
Yarnspirations features a single crochet ripple afghan pattern for beginners. The pattern's blue, yellow and pink ripples make it a great project for baby shower gifts.
Premium crochet patterns are also available online. Ravelry sales a pattern for a unique round ripple afghan. The pattern uses seven bold colors, but it is easy to change colors or to use fewer colors.