Make coffee using your preferred brewing method.
While the coffee is brewing, add milk to the pan and place it on the stove on medium heat. Alternatively, you can heat your milk in the microwave. Just make sure to do it in short intervals of 30 seconds or less to prevent the milk from boiling over.
The bubbles will start forming on the surface right before the milk starts boiling. Once that happens, whisk the milk a few times to add some air before removing it from the stove.
For better results, you can put your warm milk into a French press and push the plunger up and down to create a nice velvety foam. Make sure to only fill it halfway as the milk expands more than you would think.
Fill the mug with brewed coffee, then top with steamed milk.