In looking at some of the finished objects on Ravelry, I was worried about ending up with wonky looking circles so I came up with a little plan.
Start with a stencil and a water soluble fabric marker.
The marker is fine tipped and pretty light but if you look closely you can see the blue outline.
Then, following the pattern directions, I crocheted a circle onto the tan square.
Then I whipped stitched around the crocheted circle.
The circle still isn't as neat as I had hoped but I can live with it. The whip stitching takes forever. (Notice how the circle is only 3/4 of the way done?)
The only flaw in my plan? Notice the color of the pen? Notice the color of the other solid square? It looks like I'm going back to the craft store.