When listening to this mediation for the first time, make sure that you are sitting comfortably with your feet resting on the floor and your hands on your legs not touching.
Afterwards, feel free to do this meditation in a lotus position, standing or even lying. It doesn't matter. What matters is that you are uninterrupted and in a safe environment. It goes without saying that you shouldn't be doing this meditation while driving or handling heavy machinery. :)
As with all meditations, relax, be present and don't judge any thoughts that come to you. Just let them pass. Enjoy!
If you start feeling tingling in your feet, it's totally normal. It's a sign that the energy in you is moving. I personally yawn when I connect to the earth's energy. I also get tingles in my feet and hands.