Manual stretching is a great way to warm up and warm down for a hanging session. I suggest doing a brief 10 minute manual stretch warm up and a 5-10 minute manual stretch warm down. Stretch in every direction despite the fact that you should be exclusively lig hanging. There are a lot of tendons and ligaments you can activate and involve in a lig hanging routine if you show them attention every now and then. It'll also help you fit into your hanger better. If you're already loose, attaching a hanger should be very simple.