Jersey fabric is very difficult to work with as it stretched everywhere! My top tip and secret weapon is interfacing, simply iron it onto the back of your fabric before you begin any work. Use the lightest interfacing you can find so you still get that lovely soft feel to the jersey.
I embroidered all the facial features after interfacing, as it made it a lot easier. I even interfaced the little sewn on details to the face here too. it just make them a little easier to work with and to help me get that nice blanket stitch edge.