You should stitch around all of the appliques with a straight stitch. This will be right next to the appliques, on the background fabric. That will help the appliques to pop forward. Since this quilt looks like you'll be using it, I'd do some different designs in the remaining blocks, but nothing too dense or the quilt might become stiff. Perhaps keep your scale around 1.5"- 2", so keep your quilting lines that far apart. This is pretty remarkable for your first quilt. Check out Leah Day's website - Free Motion Project.com. She has hundreds of designs all with short videos of her demonstrating them.