Ensure butter, eggs, and buttermilk are truly at room temperature for optimal creaming and batter consistency. When zesting lemons, only remove the yellow part, avoiding the bitter white pith. Do not overmix the batter once the dry ingredients are added; stop mixing as soon as combined to prevent tough cake. Spoon the warm lemon syrup over the cakes immediately after removing them from the pans while they are still warm to maximize absorption. Allow cakes to cool completely before applying the glaze to prevent it from melting off.