Summarize the following:
Get your neck loose by rotating it around gently a few times and stretch your shoulders out by rotating them around your body. Roll your neck around clockwise five times, then counter-clockwise for a simple neck stretch. Wrap each arm around your body as if you were giving yourself a hug. With your other arm, hold it in place for a count of 15, then repeat with the other arm. Relax your shoulders and your hand. Don't clench your fist. Imagine someone where pushing on your fingertips and pushing your arm straight back. Loosen up your shoulder a bit. Bring your arm across your body as far as it can, bring your elbow as close as possible to your mouth. This is the tricky part and can cause some discomfort. Use your left hand to guide back the right arm, keeping your shoulder back as possible. Stretch your neck forward, chin out, as far as you can. Try to think of it like you're going to grab your elbow with your chin. This will help you get the most distance out of your stretch. If you've got the right build for it, you should be able to stretch your tongue to your elbow in this position. If at this point, you can't touch your tongue to your elbow, stop. This stretch will get your elbow as close as possible to your mouth as possible. If you can't, it's because your upper arm is too long and no amount of stretching will make it happen. Don't risk hyperextending your shoulder by yanking on it too hard.

Summary:
Be gentle and warm up with some stretches first. Hold your right arm out straight with your palm flat. Pull back your shoulder as far as you can so your shoulder blade stick out. Wrap your arm around your chin. Push/pull your arm backward. Crane your neck forward. Stick your tongue out as far as it will go.