I find guided meditation the easiest to follow. The "empty your head" thing I don't think is possible for me. So let's say it's guided audio on deep breathing and a countdown from 20. Breathing in, I imagine the number taking shape. Could be a sports jersey, someone's upcoming birthday or anniversary, anything associated with the number. Hold the breath, let the number solidify. Exhale, the number fades or gets blown away. Repeat, letting the audio keep me on track. My mind will wander. It's inconsequential. The audio will either bring me back, or not. I can try again later.

The most important thing is that any form of mediation takes practice. It's a skill like any other. It's often suggested in therapeutic settings, usually for grounding etc. But it should be practiced while not in distress for it to be reliably there to lean on for the time you really need it.