My favorite tip for sewing with knits is the double needle hem. I use a 4 mm double needle with wooly nylon in the bobbin. Pin up the hem very evenly and stitch from the right side of the garment. With this hem, you will still have lots of stretch in the hem and will not be popping stitches when the fabric stretches.
I also used this method to topstitch around the neckline after I finished it with a self-fabric "ribbing". This picture shows the front neckline and the inside of the back neckline.
I'm off to the game. Go Big Red!!!