Use starchy potatoes like Yukon Gold or Russet
Cook the potatoes until very tender
Drain them well
Let excess moisture evaporate in the hot pot
Mash while the potatoes are still hot
Add warm butter first
Add warm milk, cream, or half-and-half gradually
Use a potato ricer or food mill for the smoothest texture
Avoid overmixing
Season with salt
Add sour cream or cream cheese for extra richness
Use enough fat and liquid to reach a smooth consistency
Keep the potatoes warm before serving