Prepare your milk by using one of the recommended methods in the post - either in a stainless steel steamer cup or steamer appliance. If using a blender, a handheld frother, or shaking in a jar, warm the milk in a small saucepan over medium heat till just beginning to bubble.
If using a latte machine/steamer - swirl the stainless steel cup at an angle for about 1-2 minutes until milk is fully heated through. Continuously moving the cup in a steady, circular motion at this angle will help to get the milk nice and frothy.
Pour into a mug and top with cinnamon or pumpkin spice blend and vanilla extract. Stir with a spoon to incorporate both and add sweetener as needed (I personally don't think it needs any).
Notes
See post recommendations for preferred pumpkin spice blends. Both that and cinnamon will work. I tend to prefer 1/2 teaspoon in my milk, but start with 1/4 and see what you think.
Maple syrup is a great way to sweeten this, if desired.
I like to use a good vanilla extract for this. Trader Joe's has a good alcohol free one, and Nielsen Massey is my other favorite.