Reinforcing your power of hearing you sit upright or lie on your back with your knees raise lightly with a cushion and listen. That's all. When your mind starts to wander you start practicing discipline by making yourself listen again and again. To everything. And anything. Every new noise is interesting, though it wasn't before, and you start to chill.
After my first shot I feel that I want to do it every day. It's an easy way of stepping into the world of meditation without much effort and maximum effect and without feeling like a complete nonce - which is nice!