Great mashed potatoes begin with Yukon Gold potatoes, the BEST potatoes for mashing. Texture matters and is different for everybody. If you have a personal preference as to lumpy or smooth or light and airy, know what tools you need to achieve that texture. Begin 'building' your potatoes by adding a fat first. In this recipe, it's butter and by adding it at the beginning, you are ensuring the texture of the potatoes are maintained before adding liquids. Season the fat with good old Kosher salt and freshly cracked black pepper. TASTE! If it still needs seasoning, season some more before adding in liquids such as milk or cream. And as for those liquids, don't feel like you need to add them all at once. Adding a little at a time allows the potatoes to soak up all that creamy goodness and avoids gummy or watery potatoes.