I tried out the Jean Muir hem technique that Ginny brought up at Sew Incredibles recently. This is also covered in Marcy Tilton's book, Easy Guide to Sewing Tops and T-Shirts. It definitely improves the hems, giving them more weight and definition.
I used an old TNT Stretch-N-Sew technique from the 70's for the neckline. It's strip cut cross grain 2 inches wide, longer than needed for the finished neckline. First sew the binding to the neck edge, about one-to-one using a 1/2 inch SA. The jersey stretches a little as you go and this creates enough *give* in the seam. Then wrap the binding to the inside and stitch-in-the-ditch from the top. It's OK to trim the inside but I think it's more secure with the remaining SA left intact.